PROJ

https://proj.org/en/stable/
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### Install Git

Source: https://proj.org/en/stable/install.html

Installs Git, a version control system essential for cloning repositories.

```shell
cd c:\dev
git clone https://github.com/Microsoft/vcpkg.git

cd vcpkg
.\bootstrap-vcpkg.bat

```

--------------------------------

### Install Clang Tools

Source: https://proj.org/en/stable/community/code_contributions.html

Install the necessary clang tools for using the Clang Static Analyzer locally on Debian-like systems.

```bash
sudo apt install clang-tools libfindbin-libs-perl

```

--------------------------------

### Configure, Build, and Install PROJ with CMake

Source: https://proj.org/en/stable/install.html

Use CMake to configure the build, compile the source code, and install the PROJ binaries and libraries.

```bash
cmake ..
cmake --build .
cmake --build . --target install
```

--------------------------------

### Install PROJ on Windows using OSGeo4W Installer

Source: https://proj.org/en/stable/install.html

Installs PROJ on Windows via the OSGeo4W installer. This command-line approach automates the GUI steps for advanced users.

```bash
C:\temp\osgeo4w-setup.exe -q -k -r -A -s https://download.osgeo.org/osgeo4w/v2/ -P proj
```

--------------------------------

### Install PROJ on Fedora using DNF

Source: https://proj.org/en/stable/install.html

Installs PROJ on Fedora Linux using the DNF package manager.

```bash
sudo dnf install proj
```

--------------------------------

### Complete C++ PROJ Coordinate Transformation Example

Source: https://proj.org/en/stable/development/quickstart_cpp.html

A full C++ program demonstrating coordinate transformation from EPSG:4326 to EPSG:32631 using the PROJ library. Includes setup, transformation, and cleanup.

```cpp
#include <cassert>
#include <cmath>   // for HUGE_VAL
#include <iomanip> // for std::setprecision()

#include <iostream>

#include "proj/coordinateoperation.hpp"
#include "proj/crs.hpp"
#include "proj/io.hpp"
#include "proj/util.hpp" // for nn_dynamic_pointer_cast

using namespace NS_PROJ::crs;
using namespace NS_PROJ::io;
using namespace NS_PROJ::operation;
using namespace NS_PROJ::util;

int main(void) {
    auto dbContext = DatabaseContext::create();

    // Instantiate a generic authority factory, that is not tied to a particular
    // authority, to be able to get transformations registered by different
    // authorities. This can only be used for CoordinateOperationContext.
    auto authFactory = AuthorityFactory::create(dbContext, std::string());

    // Create a coordinate operation context, that can be customized to amend
    // the way coordinate operations are computed. Here we ask for default
    // settings.
    auto coord_op_ctxt =
        CoordinateOperationContext::create(authFactory, nullptr, 0.0);

    // Instantiate a authority factory for EPSG related objects.
    auto authFactoryEPSG = AuthorityFactory::create(dbContext, "EPSG");

    // Instantiate source CRS from EPSG code
    auto sourceCRS = authFactoryEPSG->createCoordinateReferenceSystem("4326");

    // Instantiate target CRS from PROJ.4 string (commented out, the equivalent
    // from the EPSG code)
    // auto targetCRS =
    // authFactoryEPSG->createCoordinateReferenceSystem("32631");
    auto targetCRS =
        NN_CHECK_THROW(nn_dynamic_pointer_cast<CRS>(createFromUserInput(
            "+proj=utm +zone=31 +datum=WGS84 +type=crs", dbContext)));

    // List operations available to transform from EPSG:4326
    // (WGS 84 latitude/longitude) to EPSG:32631 (WGS 84 / UTM zone 31N).
    auto list = CoordinateOperationFactory::create()->createOperations(
        sourceCRS, targetCRS, coord_op_ctxt);

    // Check that we got a non-empty list of operations
    // The list is sorted from the most relevant to the less relevant one.
    // Cf
    // https://proj.org/operations/operations_computation.html#filtering-and-sorting-of-coordinate-operations
    // for more details on the sorting of those operations.
    // For a transformation between a projected CRS and its base CRS, like
    // we do here, there will be only one operation.
    assert(!list.empty());

    // Create an execution context (must only be used by one thread at a time)
    PJ_CONTEXT *ctx = proj_context_create();

    // Create a coordinate transformer from the first operation of the list
    auto transformer = list[0]->coordinateTransformer(ctx);

    // Perform the coordinate transformation.
    PJ_COORD c = {{ 
        49.0,    // latitude in degree
        2.0,     // longitude in degree
        0.0,     // z ordinate. unused
        HUGE_VAL // time ordinate. unused
    }};
    c = transformer->transform(c);

    // Display result
    std::cout << std::fixed << std::setprecision(3);
    std::cout << "Easting: " << c.v[0] << std::endl;  // should be 426857.988
    std::cout << "Northing: " << c.v[1] << std::endl; // should be 5427937.523

    // Destroy execution context
    proj_context_destroy(ctx);

    return 0;
}

```

--------------------------------

### Install PROJ on macOS using Homebrew

Source: https://proj.org/en/stable/install.html

Installs PROJ on macOS using the Homebrew package manager. Ensure Homebrew is installed.

```bash
brew install proj
```

--------------------------------

### Install PROJ on Debian/Ubuntu using APT

Source: https://proj.org/en/stable/install.html

Installs the PROJ binary package on Debian-based Linux distributions using the APT package manager.

```bash
sudo apt-get install proj-bin
```

--------------------------------

### Install GFortran on Ubuntu

Source: https://proj.org/en/stable/resource_files.html

Installs the GFortran compiler on Ubuntu systems, required for compiling the HTDP program.

```bash
apt-get install gfortran

```

--------------------------------

### Install Pre-commit Hooks

Source: https://proj.org/en/stable/development/dev_practices.html

Install pre-commit hooks to automatically run code linters before committing. This ensures code quality and consistency.

```bash
python -m pip install pre-commit
pre-commit install

```

--------------------------------

### Install PROJ on macOS using MacPorts

Source: https://proj.org/en/stable/install.html

Installs PROJ on macOS using the MacPorts package manager. Ensure MacPorts is installed.

```bash
sudo ports install proj
```

--------------------------------

### Forward Projection Example (Sphere)

Source: https://proj.org/en/stable/operations/projections/eqearth.html

Demonstrates a forward projection on a sphere with a specified radius. Ensure the input coordinates are in decimal degrees.

```bash
$ echo 122 47 | proj +proj=eqearth +R=1
1.55    0.89

```

--------------------------------

### Peirce Quincuncial Projection Examples

Source: https://proj.org/en/stable/operations/projections/peirce_q.html

Examples of proj-strings for the Peirce Quincuncial projection with different shape options.

```APIDOC
## Peirce Quincuncial Projection Examples

### Description
Examples of proj-strings for the Peirce Quincuncial projection with different shape options.

### Code Snippets

#### Square Shape
```proj
+proj=peirce_q +lon_0=25 +shape=square
```

#### Diamond Shape
```proj
+proj=peirce_q +lon_0=25 +shape=diamond
```

#### Horizontal Shape
```proj
+proj=peirce_q +lon_0=25 +shape=horizontal
```

#### Grieger Triptychial Projection (Oblique Transformation)
```proj
+proj=pipeline +step +proj=ob_tran +o_proj=peirce_q +o_lat_p=-45 +o_lon_p=45 +o_type=horizontal +o_scrollx=-0.25 +step +proj=affine +s11=-1 +s12=0 +s21=0 +s22=-1
```
```

--------------------------------

### Complete C API Example

Source: https://proj.org/en/stable/development/quickstart.html

A full compilable C program demonstrating coordinate transformation from EPSG:4326 to UTM zone 32 and back, including normalization.

```c
#include <proj.h>
#include <stdio.h>

int main(void) {
    PJ_CONTEXT *C;
    PJ *P;
    PJ *norm;
    PJ_COORD a, b;

    /* or you may set C=PJ_DEFAULT_CTX if you are sure you will     */
    /* use PJ objects from only one thread                          */
    C = proj_context_create();

    P = proj_create_crs_to_crs(
        C, "EPSG:4326", "+proj=utm +zone=32 +datum=WGS84", /* or EPSG:32632 */
        NULL);

    if (0 == P) {
        fprintf(stderr, "Failed to create transformation object.\n");
        return 1;
    }

    /* This will ensure that the order of coordinates for the input CRS */
    /* will be longitude, latitude, whereas EPSG:4326 mandates latitude, */
    /* longitude */
    norm = proj_normalize_for_visualization(C, P);
    if (0 == norm) {
        fprintf(stderr, "Failed to normalize transformation object.\n");
        return 1;
    }
    proj_destroy(P);
    P = norm;

    /* a coordinate union representing Copenhagen: 55d N, 12d E */
    /* Given that we have used proj_normalize_for_visualization(), the order */
    /* of coordinates is longitude, latitude, and values are expressed in */
    /* degrees. */
    a = proj_coord(12, 55, 0, 0);

    /* transform to UTM zone 32, then back to geographical */
    b = proj_trans(P, PJ_FWD, a);
    printf("easting: %.3f, northing: %.3f\n", b.enu.e, b.enu.n);

    b = proj_trans(P, PJ_INV, b);
    printf("longitude: %g, latitude: %g\n", b.lp.lam, b.lp.phi);

    /* Clean up */
    proj_destroy(P);
    proj_context_destroy(C); /* may be omitted in the single threaded case */
    return 0;
}
```

--------------------------------

### Install PROJ using Conda

Source: https://proj.org/en/stable/install.html

Installs the PROJ package from the conda-forge channel. Ensure you have conda installed and configured.

```bash
conda install -c conda-forge proj
```

--------------------------------

### No Operation Conversion Example

Source: https://proj.org/en/stable/operations/conversions/noop.html

This example demonstrates passing coordinates through the noop conversion using the cct command-line tool. The input coordinates are returned exactly as they were provided.

```bash
$ echo 12 34 56 78 | cct +proj=noop
  12.0000        34.0000       56.0000       78.0000

```

--------------------------------

### PROJ v.5: Coordinate Transformation Example

Source: https://proj.org/en/stable/development/migration.html

Implements the same coordinate conversion as the v.4 example but using the newer PROJ v.5 API. Features updated header, data types, and transformation functions.

```c
#include <proj.h>

main(int argc, char **argv) {
    PJ *P;
    PJ_COORD c;

    P = proj_create(PJ_DEFAULT_CTX, "+proj=merc +ellps=clrk66 +lat_ts=33");
    if (P==0)
        return 1;

    while (scanf("%lf %lf", &c.lp.lam, &c.lp.phi) == 2) {
        c.lp.lam = proj_torad(c.lp.lam);
        c.lp.phi = proj_torad(c.lp.phi);
        c = proj_trans(P, PJ_FWD, c);
        printf("%.2f\t%.2f\n", c.xy.x, c.xy.y);
    }

    proj_destroy(P);
}


```

--------------------------------

### PROJJSON Example URL

Source: https://proj.org/en/stable/specifications/projjson.html

An example URL demonstrating how to access CRS definitions in PROJJSON format from the spatialreference.org website.

```url
https://spatialreference.org/ref/epsg/4326/projjson.json
```

--------------------------------

### Inverse Projection Example

Source: https://proj.org/en/stable/operations/projections/natearth.html

Demonstrates an inverse projection on a sphere with a specified radius. Ensure the 'proj' command-line tool is available.

```bash
$ echo 3500 -8000 | proj -I +proj=natearth +a=7500
37d54'6.091"E  61d23'4.582"S

```

--------------------------------

### Install PROJ Dependencies with vcpkg

Source: https://proj.org/en/stable/install.html

Installs PROJ dependencies sqlite3, tiff, and curl using vcpkg for both x86 and x64 Windows triplets. Note that tiff and curl are only needed for PROJ versions 7.0 and later.

```shell
vcpkg install sqlite3[core,tool] tiff curl --triplet=x86-windows
vcpkg install sqlite3[core,tool] tiff curl --triplet=x64-windows

```

--------------------------------

### PROJ 4 to 5 API Migration: cs2cs vs cct Example

Source: https://proj.org/en/stable/development/migration.html

Demonstrates the difference in transforming coordinates between PROJ 4 (using `cs2cs`) and PROJ 5 (using `cct`). The PROJ 5 example uses `+inv` for inverse transformation within a pipeline.

```bash
$ echo 300000 6100000 | cs2cs +proj=utm +zone=33 +ellps=GRS80 +to +proj=utm +zone=32 +ellps=GRS80
683687.87       6099299.66 0.00
```

```bash
$ echo 300000 6100000 0 0 | cct +proj=pipeline +step +inv +proj=utm +zone=33 +ellps=GRS80 +step +proj=utm +zone=32 +ellps=GRS80
683687.8667   6099299.6624    0.0000    0.0000
```

--------------------------------

### Example Grid Type Item

Source: https://proj.org/en/stable/specifications/geodetictiffgrids.html

This snippet shows an example of how to specify the TYPE for a grid within an Item element.

```xml
<Item name="TYPE">HORIZONTAL_OFFSET</Item>
```

--------------------------------

### Mercator Projection Usage Examples

Source: https://proj.org/en/stable/operations/projections/merc.html

Examples demonstrating the usage of the Mercator projection with different parameters.

```APIDOC
## Mercator Projection Usage

Applications should be limited to equatorial regions, but is frequently used for navigational charts with latitude of true scale (`+lat_ts`) specified within or near chart's boundaries. It is considered to be inappropriate for world maps because of the gross distortions in area; for example the projected area of Greenland is larger than that of South America, despite the fact that Greenland's area is 1/8 that of South America [Snyder1987].

### Example using latitude of true scale:
```
$ echo 56.35 12.32 | proj +proj=merc +lat_ts=56.5
3470306.37    759599.90
```

### Example using scaling factor:
```
echo 56.35 12.32 | proj +proj=merc +k_0=2
12545706.61     2746073.80
```

Note that `+lat_ts` and `+k_0` are mutually exclusive. If used together, `+lat_ts` takes precedence over `+k_0`.
```

--------------------------------

### Install PROJ using Docker

Source: https://proj.org/en/stable/install.html

Pulls the official PROJ Docker image, which includes binaries and grid shift files. Useful for containerized environments.

```bash
docker pull osgeo/proj
```

--------------------------------

### Spatiotemporal Transformation Example

Source: https://proj.org/en/stable/tutorials/EUREF2019/exercises/helmert.html

This example demonstrates a spatiotemporal transformation, showing input coordinates with a time tag (decimal year) and the expected output coordinates. Note that the time component is always required for spatiotemporal transformations in PROJ and is not altered by the transformation itself. Pay attention to parameter units, converting them to standard units like meters if necessary.

```text
operation   <your answer here>
tolerance   1 mm


accept      2952736.3768   1360917.6894  5468849.5615       2019.5
expect      2952736.3744   1360917.6871  5468849.5586       2019.5
```

--------------------------------

### Install PROJ Data Package using Conda

Source: https://proj.org/en/stable/install.html

Installs the PROJ data package, which includes necessary grid shift files. Recommended for full functionality.

```bash
conda install -c conda-forge proj-data
```

--------------------------------

### Set coordinate value pipeline example

Source: https://proj.org/en/stable/operations/conversions/set.html

This example demonstrates setting the ellipsoidal ETRS89 height to 43m for a Helmert transformation and then to 0m for reverse direction usability. It showcases a complex pipeline involving unit conversion, axis swapping, grid shifts, and coordinate transformations.

```bash
$ cct -t 0 -d 4 +proj=pipeline \
     +step +proj=unitconvert +xy_in=deg +xy_out=rad \
     +step +proj=axisswap +order=2,1 \
     +step +proj=vgridshift +grids=nlgeo2018.gtx \
     +step +proj=push +v_3 \
     +step +proj=set +v_3=43 \
     +step +proj=cart \
     +step +proj=helmert +x=-565.7346 +y=-50.4058 +z=-465.2895 +rx=-0.395023 +ry=0.330776 +rz=-1.876073 +s=-4.07242 +convention=coordinate_frame +exact \
     +step +proj=cart +inv +ellps=bessel \
     +step +proj=hgridshift +inv +grids=rdcorr2018.gsb,null \
     +step +proj=sterea +lat_0=52.156160556 +lon_0=5.387638889 +k=0.9999079 +x_0=155000 +y_0=463000 +ellps=bessel \
     +step +proj=set +v_3=0 \
     +step +proj=pop +v_3

```

--------------------------------

### PROJ Transformation Example with cs2cs

Source: https://proj.org/en/stable/resource_files.html

This command demonstrates how to use a generated CTable2 grid shift file with the `cs2cs` utility for transforming coordinates between NAD83 and WGS84 datums.

```bash
cs2cs +proj=latlong +ellps=GRS80 +nadgrids=./nad83_2002.ct2 +to +proj=latlong +datum=WGS84
```

--------------------------------

### Create and Navigate to Build Directory

Source: https://proj.org/en/stable/install.html

Create a separate directory for building PROJ and change into it. This keeps the source tree clean.

```bash
mkdir build
cd build
```

--------------------------------

### Uninstall PROJ

Source: https://proj.org/en/stable/install.html

Remove files installed by the 'install' target using the 'uninstall' CMake target. Available starting with PROJ 9.2.

```bash
cmake --build . --target uninstall
```

--------------------------------

### TemporalExtent

Source: https://proj.org/en/stable/development/reference/cpp/metadata.html

Represents the time period covered by the content of a dataset. Provides methods to get the start and end times, and to check for containment and intersection with other temporal extents.

```APIDOC
## TemporalExtent

### Description
Time period covered by the content of the dataset. Simplified version of TemporalExtent from GeoAPI.

### Public Functions

- **start()** - `const std::string &` - Returns the start of the temporal extent.
- **stop()** - `const std::string &` - Returns the end of the temporal extent.
- **contains(const TemporalExtentNNPtr &other)** - `bool` - Returns whether this extent contains the other one.
- **intersects(const TemporalExtentNNPtr &other)** - `bool` - Returns whether this extent intersects the other one.

### Public Static Functions

- **create(const std::string &start, const std::string &stop)** - `TemporalExtentNNPtr` - Instantiate a TemporalExtent.
  - Parameters:
    - **start** - `const std::string &` - start.
    - **stop** - `const std::string &` - stop.
  - Returns:
    - `TemporalExtentNNPtr` - a new TemporalExtent.
```

--------------------------------

### Forward Projection Example - Bertin 1953

Source: https://proj.org/en/stable/operations/projections/bertin1953.html

Demonstrates a forward projection using the Bertin 1953 method with a specified radius. This is useful for general world map creation.

```bash
$ echo 122 47 | proj +proj=bertin1953 +R=1
0.72    0.73

```

--------------------------------

### Web Mercator Forward Projection Example

Source: https://proj.org/en/stable/operations/projections/webmerc.html

Demonstrates how to perform a forward projection using the Web Mercator method with specific input coordinates and the WGS84 datum. Ensure the 'proj' command-line tool is available.

```bash
$ echo 2 49 | proj +proj=webmerc +datum=WGS84
222638.98       6274861.39

```

--------------------------------

### Get PROJ Library Information

Source: https://proj.org/en/stable/development/reference/functions.html

Retrieves general information about the current PROJ library instance, such as version and build details.

```c
PJ_INFO proj_info(void)
```

--------------------------------

### PROJ Init File Format

Source: https://proj.org/en/stable/resource_files.html

Init files define pre-configured PROJ strings, often for transformations to WGS84. This example shows the format for defining a coordinate reference system using its EPSG ID and a PROJ string.

```plaintext
<3819> +proj=longlat +ellps=bessel
       +towgs84=595.48,121.69,515.35,4.115,-2.9383,0.853,-3.408 +no_defs <>
```

--------------------------------

### PROJ Init File Metadata Entry

Source: https://proj.org/en/stable/resource_files.html

This example shows a special metadata entry format accepted in PROJ init files since version 4.10.0, providing version and origin information.

```plaintext
<metadata> +version=9.0.0 +origin=EPSG +lastupdate=2017-01-10
```

--------------------------------

### Create PROJ Database Context

Source: https://proj.org/en/stable/development/quickstart_cpp.html

Instantiate a DatabaseContext with default settings to locate the PROJ data files.

```cpp
auto dbContext = DatabaseContext::create();


```

--------------------------------

### Download All Resource Files with projsync

Source: https://proj.org/en/stable/apps/projsync.html

Use this command to download all available resource files. This is a straightforward way to ensure you have the complete dataset.

```bash
projsync --all
```

--------------------------------

### create(const util::PropertyMap &propertiesConversion, const util::PropertyMap &propertiesOperationMethod, const std::vector<OperationParameterNNPtr> &parameters, const std::vector<ParameterValueNNPtr> &values)

Source: https://proj.org/en/stable/development/reference/cpp/operation.html

Instantiates a Conversion and its OperationMethod using provided properties, parameters, and values.

```APIDOC
## create(const util::PropertyMap &propertiesConversion, const util::PropertyMap &propertiesOperationMethod, const std::vector<OperationParameterNNPtr> &parameters, const std::vector<ParameterValueNNPtr> &values)

### Description
Instantiate a Conversion and its OperationMethod.

### Parameters:
#### Path Parameters
* **propertiesConversion** (util::PropertyMap) - See General properties of the conversion. At minimum the name should be defined.
* **propertiesOperationMethod** (util::PropertyMap) - See General properties of the operation method. At minimum the name should be defined.
* **parameters** (std::vector<OperationParameterNNPtr>) - the operation parameters.
* **values** (std::vector<ParameterValueNNPtr>) - the operation values. Constraint: values.size() == parameters.size()

### Throws:
InvalidOperation -- if the object cannot be constructed.

### Returns:
a new Conversion.
```

--------------------------------

### Using Init Files with cs2cs

Source: https://proj.org/en/stable/resource_files.html

This command demonstrates how to use a pre-configured PROJ string from an init file (e.g., epsg:3819) with the `cs2cs` utility for coordinate system transformations.

```bash
$ cs2cs -v +proj=latlong +to +init=epsg:3819
# ---- From Coordinate System ----
#Lat/long (Geodetic alias)
#
# +proj=latlong +ellps=WGS84
# ---- To Coordinate System ----
#Lat/long (Geodetic alias)
#
# +init=epsg:3819 +proj=longlat +ellps=bessel
```

--------------------------------

### Python as a command-line calculator

Source: https://proj.org/en/stable/tutorials/geodesics.html

Demonstrates using Python as a simple command-line calculator for basic arithmetic operations.

```python
python -c print((4+8)/2)
```

--------------------------------

### Sample gie Test File

Source: https://proj.org/en/stable/apps/gie.html

A basic gie test file demonstrating the operation, accept, and expect commands within <gie> tags. Comments and styling can be added to improve readability.

```gie
<gie>

--------------------------------------------
Test output of the UTM projection
--------------------------------------------
operation  +proj=utm  +zone=32  +ellps=GRS80
--------------------------------------------
accept     12  55
expect     691_875.632_14   6_098_907.825_05

</gie>
```

--------------------------------

### Pipeline with Inverse Step

Source: https://proj.org/en/stable/operations/pipeline.html

Example of using the +inv parameter to invert a specific step within a pipeline. This example uses UTM and its inverse.

```PROJ
echo -88 42 0 0|cct +zone=16 +proj=pipeline +step +proj=utm +step +proj=utm +inv
```

--------------------------------

### Pipeline with Global Parameters

Source: https://proj.org/en/stable/operations/pipeline.html

Illustrates how parameters defined before the first +step are applied globally to all subsequent steps.

```PROJ
+proj=pipeline +ellps=GRS80
+step +proj=cart
+step +proj=helmert +x=10 +y=3 +z=1
+step +proj=cart +inv
+step +proj=merc
```

--------------------------------

### Gauss-Kruger Projection Example

Source: https://proj.org/en/stable/operations/projections/tmerc.html

Example of using the Transverse Mercator projection with Gauss-Kruger parameters for Germany. This is useful for grid-based mapping within specific regions.

```bash
$ echo 9 51 | proj +proj=tmerc +lon_0=9 +x_0=3500000 +ellps=bessel
3500000.00  5651505.56

```

--------------------------------

### createTunisiaMiningGrid

Source: https://proj.org/en/stable/development/reference/cpp/operation.html

Instantiate a conversion based on the Tunisia Mining Grid projection method (EPSG:9816). Since 9.2.

```APIDOC
## createTunisiaMiningGrid

### Description
Instantiate a conversion based on the Tunisia Mining Grid projection method. This method is defined as EPSG:9816.

**Since**
    
9.2 
Note
There is currently no implementation of the method formulas in PROJ.

### Method
static ConversionNNPtr createTunisiaMiningGrid

### Parameters
* **properties** (util::PropertyMap) - See General properties of the conversion. If the name is not provided, it is automatically set.
* **centerLat** (common::Angle) - See Latitude of natural origin/Center Latitude
* **centerLong** (common::Angle) - See Longitude of natural origin/Central Meridian
* **falseEasting** (common::Length) - See False Easting
* **falseNorthing** (common::Length) - See False Northing

### Returns
a new Conversion.
```

--------------------------------

### Cassini Projection Example (Soldner Berlin)

Source: https://proj.org/en/stable/operations/projections/cass.html

Example of using the Cassini projection with the Bessel ellipsoid for Soldner Berlin. Input coordinates are in decimal degrees.

```bash
$ echo 13.5 52.4 | proj +proj=cass \
  +lat_0=52.41864827777778 +lon_0=13.62720366666667 \
  +x_0=40000 +y_0=10000 +ellps=bessel
31343.05    7932.76

```

--------------------------------

### Run rHEALPix Projection

Source: https://proj.org/en/stable/operations/projections/rhealpix.html

Demonstrates how to perform a rHEALPix projection using the PROJ command-line utility. This example uses the default GRS80 ellipsoidal model and specifies the north_square parameter.

```bash
proj +proj=rhealpix +north_square=2 -E << EOF
> 55 12
> EOF
55 12   6115727.86  1553840.13

```

--------------------------------

### Install PROJ on Red Hat using YUM

Source: https://proj.org/en/stable/install.html

Installs PROJ on Red Hat Enterprise Linux and similar distributions using the YUM package manager.

```bash
sudo yum install proj
```

--------------------------------

### Standard Molodensky Transform Example

Source: https://proj.org/en/stable/operations/transformations/molodensky.html

This example shows the standard Molodensky transform. It uses the same parameters as the abridged version but without the 'abridged' flag for a more precise calculation.

```plaintext
proj=molodensky a=6378160 rf=298.25 da=-23 df=-8.120449e-8  dx=-134 dy=-48 dz=149
```

--------------------------------

### create(properties, baseCRSIn, hubCRSIn, transformationIn)

Source: https://proj.org/en/stable/development/reference/cpp/crs.html

Instantiates a BoundCRS from a base CRS, a hub CRS, and a transformation with properties.

```APIDOC
## create(const util::PropertyMap &properties, const CRSNNPtr &baseCRSIn, const CRSNNPtr &hubCRSIn, const operation::TransformationNNPtr &transformationIn)

### Description
Instantiate a BoundCRS from a base CRS, a hub CRS and a transformation.

### Parameters
- **properties** (util::PropertyMap) - See General properties.
- **baseCRSIn** (CRSNNPtr) - base CRS.
- **hubCRSIn** (CRSNNPtr) - hub CRS.
- **transformationIn** (operation::TransformationNNPtr) - transformation from base CRS to hub CRS.

### Returns
new BoundCRS (BoundCRSNNPtr)
```

--------------------------------

### Gauss Boaga Projection Example

Source: https://proj.org/en/stable/operations/projections/tmerc.html

Example of using the Transverse Mercator projection with Gauss Boaga parameters for Italy. This demonstrates a specific regional application of the projection.

```bash
$ echo 15 42 | proj +proj=tmerc +lon_0=15 +k_0=0.9996 +x_0=2520000 +ellps=intl
2520000.00  4649858.60

```

--------------------------------

### createTunisiaMappingGrid

Source: https://proj.org/en/stable/development/reference/cpp/operation.html

Instantiate a conversion based on the Tunisia Mapping Grid projection method (EPSG:9816). Deprecated, use createTunisiaMiningGrid() instead.

```APIDOC
## createTunisiaMappingGrid

### Description
Instantiate a conversion based on the Tunisia Mapping Grid projection method. This method is defined as EPSG:9816.

_Deprecated:_
    
. Use createTunisiaMiningGrid() instead 
Note
There is currently no implementation of the method formulas in PROJ.

### Method
static ConversionNNPtr createTunisiaMappingGrid

### Parameters
* **properties** (util::PropertyMap) - See General properties of the conversion. If the name is not provided, it is automatically set.
* **centerLat** (common::Angle) - See Latitude of natural origin/Center Latitude
* **centerLong** (common::Angle) - See Longitude of natural origin/Central Meridian
* **falseEasting** (common::Length) - See False Easting
* **falseNorthing** (common::Length) - See False Northing

### Returns
a new Conversion.
```

--------------------------------

### Abridged Molodensky Transform Example

Source: https://proj.org/en/stable/operations/transformations/molodensky.html

This example demonstrates the abridged version of the Molodensky transform. It requires parameters for the ellipsoid, differences in semimajor axis and flattening, and axis offsets.

```plaintext
proj=molodensky a=6378160 rf=298.25 da=-23 df=-8.120449e-8  dx=-134 dy=-48 dz=149 abridged
```

--------------------------------

### Transforming a point with LINZ NZGD2000 deformation model

Source: https://proj.org/en/stable/operations/transformations/defmodel.html

Use this example to transform a point using the LINZ NZGD2000 deformation model. Ensure the JSON master file is correctly specified.

```bash
echo 166.7133850980 -44.5105886020 293.3700 2007.689 |
     cct +proj=defmodel +model=nzgd2000-20180701.json

```

--------------------------------

### Cassini Projection Example (EPSG 30200)

Source: https://proj.org/en/stable/operations/projections/cass.html

Example of using the Cassini projection with specific parameters for Trinidad 1903. Ensure input coordinates are in decimal degrees and output is in meters.

```bash
$ echo 0.17453293 -1.08210414 | proj +proj=cass \
  +lat_0=10.44166666666667 +lon_0=-61.33333333333334 \
  +x_0=86501.46392051999 +y_0=65379.0134283 \
  +a=6378293.645208759 +b=6356617.987679838 \
  +to_meter=0.201166195164
66644.94    82536.22

```

--------------------------------

### Real Polynomial Horner Transformation Example

Source: https://proj.org/en/stable/operations/transformations/horner.html

Example of setting up a Horner transformation using real polynomials for mapping between Danish TC32 and ETRS89/UTM zone 32. This configuration uses a 4th-degree polynomial.

```proj
+proj=horner
+ellps=intl
+range=500000
+fwd_origin=877605.269066,6125810.306769
+inv_origin=877605.760036,6125811.281773
+deg=4
+fwd_v=6.1258112678e+06,9.9999971567e-01,1.5372750011e-10,5.9300860915e-15,2.2609497633e-19,4.3188227445e-05,2.8225130416e-10,7.8740007114e-16,-1.7453997279e-19,1.6877465415e-10,-1.1234649773e-14,-1.7042333358e-18,-7.9303467953e-15,-5.2906832535e-19,3.9984284847e-19
+fwd_u=8.7760574982e+05,9.9999752475e-01,2.8817299305e-10,5.5641310680e-15,-1.5544700949e-18,-4.1357045890e-05,4.2106213519e-11,2.8525551629e-14,-1.9107771273e-18,3.3615590093e-10,2.4380247154e-14,-2.0241230315e-18,1.2429019719e-15,5.3886155968e-19,-1.0167505000e-18
+inv_v=6.1258103208e+06,1.0000002826e+00,-1.5372762184e-10,-5.9304261011e-15,-2.2612705361e-19,-4.3188331419e-05,-2.8225549995e-10,-7.8529116371e-16,1.7476576773e-19,-1.6875687989e-10,1.1236475299e-14,1.7042518057e-18,7.9300735257e-15,5.2881862699e-19,-3.9990736798e-19
+inv_u=8.7760527928e+05,1.0000024735e+00,-2.8817540032e-10,-5.5627059451e-15,1.5543637570e-18,4.1357152105e-05,-4.2114813612e-11,-2.8523713454e-14,1.9109017837e-18,-3.3616407783e-10,-2.4382678126e-14,2.0245020199e-18,-1.2441377565e-15,-5.3885232238e-19,1.0167203661e-18
```

--------------------------------

### Complex Polynomial Horner Transformation Example

Source: https://proj.org/en/stable/operations/transformations/horner.html

Example of setting up a Horner transformation using complex polynomials for mapping between Danish System Storebælt and ETRS89/UTM zone 32. This configuration uses a 3rd-degree polynomial.

```proj
+proj=horner
+ellps=intl
+range=500000
+fwd_origin=4.94690026817276e+05,6.13342113183056e+06
+inv_origin=6.19480258923588e+05,6.13258568148837e+06
+deg=3
+fwd_c=6.13258562111350e+06,6.19480105709997e+05,9.99378966275206e-01,-2.82153291753490e-02,-2.27089979140026e-10,-1.77019590701470e-09,1.08522286274070e-14,2.11430298751604e-15
+inv_c=6.13342118787027e+06,4.94690181709311e+05,9.99824464710368e-01,2.82279070814774e-02,7.66123542220864e-11,1.78425334628927e-09,-1.05584823306400e-14,-3.32554258683744e-15
```

--------------------------------

### Navigate to PROJ Source Directory

Source: https://proj.org/en/stable/install.html

Change the current directory to the unpacked PROJ source code directory.

```bash
cd proj-9.8.1
```

--------------------------------

### createFromUserInput (with PJ_CONTEXT)

Source: https://proj.org/en/stable/development/reference/cpp/io.html

Instantiates a sub-class of BaseObject from a user-specified text, supporting WKT and PROJ string formats, using a provided PROJ context.

```APIDOC
## createFromUserInput (with PJ_CONTEXT)

### Description
Instantiate a sub-class of BaseObject from a user specified text. The text can be a:
  * WKT string
  * PROJ string

### Parameters
#### Parameters
- **text** (string) - One of the above mentioned text format
- **ctx** (PJ_CONTEXT *) - PROJ context

### Throws
ParsingException -- if the string cannot be parsed.
```

--------------------------------

### S2 Projection Usage Example

Source: https://proj.org/en/stable/operations/projections/s2.html

This example demonstrates using the S2 projection on the right face of the cube with the linear area-normalization transformation. It takes geodetic coordinates (latitude, longitude) as input and outputs projected coordinates.

```bash
echo 90 0 | proj +proj=s2 +lat_0=0 +lon_0=90 +ellps=WGS84 +UVtoST=linear

0.5 0.5

```

--------------------------------

### DatumEnsemble::create

Source: https://proj.org/en/stable/development/reference/cpp/datum.html

Instantiate a DatumEnsemble. Requires at least 2 datums and properties including a name.

```APIDOC
## DatumEnsemble::create

### Description
Instantiate a DatumEnsemble.

### Parameters
- **properties** (`util::PropertyMap`): See General properties. At minimum the name should be defined.
- **datumsIn** (`std::vector<DatumNNPtr>`): Array of at least 2 datums.
- **accuracy** (`metadata::PositionalAccuracyNNPtr`): Accuracy of the datum ensemble

### Throws
- `util::Exception`: in case of error.

### Returns
- `DatumEnsembleNNPtr`: new DatumEnsemble.
```

--------------------------------

### Determine Location from Azimuth and Distance with geod

Source: https://proj.org/en/stable/apps/geod.html

This snippet shows how to find a destination location by providing a starting point, a forward azimuth, and a distance. The output includes the latitude, longitude, and back azimuth to the starting point.

```bash
geod +ellps=clrk66 +units=us-mi <<EOF
42d15'N 71d07'W -66d31'50.141" 2587.504
EOF
```

```text
45d31'0.003"N 123d40'59.985"W 75d39'13.094"
```

--------------------------------

### Install PROJ Dependencies with Conda

Source: https://proj.org/en/stable/install.html

Sets up a Conda environment named 'proj' and installs PROJ dependencies including sqlite, libtiff, curl, and cmake. Note that libtiff and curl are only needed for PROJ versions 7.0 and later.

```shell
cd c:\dev
conda create --name proj
conda activate proj
conda install sqlite libtiff curl cmake

```

--------------------------------

### proj_insert_object_session_destroy

Source: https://proj.org/en/stable/development/reference/functions.html

Stops an insertion session previously started with proj_insert_object_session_create().

```APIDOC
## proj_insert_object_session_destroy

### Description
Stops an insertion session started with proj_insert_object_session_create().

### Parameters
* **ctx** (PJ_CONTEXT *) - PROJ context, or NULL for default context
* **session** (PJ_INSERT_SESSION *) - The insertion session to destroy.
```

--------------------------------

### proj_as_proj_string

Source: https://proj.org/en/stable/development/reference/functions.html

Gets a PROJ string representation of a PROJ object.

```APIDOC
## proj_as_proj_string

### Description
Get a PROJ string representation of an object.
This function calls osgeo::proj::io::IPROJStringExportable::exportToPROJString().
This function may return NULL if the object is not compatible with an export to the requested type.
Warning
If a CRS object was not created from a PROJ string, exporting to a PROJ string will in most cases cause a loss of information. This can potentially lead to erroneous transformations.

### Parameters
* **ctx** -- PROJ context, or NULL for default context
* **obj** -- Object (must not be NULL)
```

--------------------------------

### proj_context_get_url_endpoint

Source: https://proj.org/en/stable/development/reference/functions.html

Get the URL endpoint to query for remote grids.

```APIDOC
## proj_context_get_url_endpoint

### Description
Get the URL endpoint to query for remote grids.

### Parameters
* **ctx** (PJ_CONTEXT *) - PROJ context, or NULL

### Returns
* **const char *** - Endpoint URL. The returned pointer would be invalidated by a later call to proj_context_set_url_endpoint()
```

--------------------------------

### createFromUserInput (with DatabaseContext)

Source: https://proj.org/en/stable/development/reference/cpp/io.html

Instantiates a sub-class of BaseObject from a user-specified text, supporting various formats like WKT, PROJ string, database codes, OGC URNs, OGC URLs, object names, and PROJJSON. It can optionally use PROJ4/PROJ5 initialization rules.

```APIDOC
## createFromUserInput (with DatabaseContext)

### Description
Instantiate a sub-class of BaseObject from a user specified text. The text can be a:
  * WKT string
  * PROJ string
  * database code, prefixed by its authority. e.g. "EPSG:4326"
  * OGC URN. e.g. "urn:ogc:def:crs:EPSG::4326", "urn:ogc:def:coordinateOperation:EPSG::1671", "urn:ogc:def:ellipsoid:EPSG::7001" or "urn:ogc:def:datum:EPSG::6326"
  * OGC URN combining references for compound coordinate reference systems e.g. "urn:ogc:def:crs,crs:EPSG::2393,crs:EPSG::5717" We also accept a custom abbreviated syntax EPSG:2393+5717 or ESRI:103668+EPSG:5703
  * OGC URN combining references for references for projected or derived CRSs e.g. for Projected 3D CRS "UTM zone 31N / WGS 84 (3D)" "urn:ogc:def:crs,crs:EPSG::4979,cs:PROJ::ENh,coordinateOperation:EPSG::16031"
  * Extension of OGC URN for CoordinateMetadata. e.g. "urn:ogc:def:coordinateMetadata:NRCAN::NAD83_CSRS_1997_MTM11_HT2_1997"
  * OGC URN combining references for concatenated operations e.g. "urn:ogc:def:coordinateOperation,coordinateOperation:EPSG::3895,coordinateOperation:EPSG::1618"
  * OGC URL for a single CRS. e.g. "http://www.opengis.net/def/crs/EPSG/0/4326"
  * OGC URL for a compound CRS. e.g "http://www.opengis.net/def/crs-compound?1=http://www.opengis.net/def/crs/EPSG/0/4326&2=http://www.opengis.net/def/crs/EPSG/0/3855"
  * an Object name. e.g "WGS 84", "WGS 84 / UTM zone 31N". In that case as uniqueness is not guaranteed, the function may apply heuristics to determine the appropriate best match.
  * a CRS name and a coordinate epoch, separated with '@'. For example "ITRF2014@2025.0". (added in PROJ 9.2)
  * a compound CRS made from two object names separated with " + ". e.g. "WGS 84 + EGM96 height"
  * PROJJSON string

### Parameters
#### Parameters
- **text** (string) - One of the above mentioned text format
- **dbContext** (DatabaseContextPtr) - Database context, or nullptr (in which case database lookups will not work)
- **usePROJ4InitRules** (bool) - When set to true, init=epsg:XXXX syntax will be allowed and will be interpreted according to PROJ.4 and PROJ.5 rules, that is geodeticCRS will have longitude, latitude order and will expect/output coordinates in radians. ProjectedCRS will have easting, northing axis order (except the ones with Transverse Mercator South Orientated projection). In that mode, the epsg:XXXX syntax will be also interpreted the same way.

### Throws
ParsingException -- if the string cannot be parsed.
```

--------------------------------

### Catch and Report PROJ Errors in C

Source: https://proj.org/en/stable/development/errorhandling.html

This example demonstrates how to check for errors after a PROJ API call and retrieve detailed error information. Ensure a `PJ_CONTEXT` is created before making PROJ API calls.

```c
#include <stdio.h>
#include <proj.h>

int main (void) {
    PJ_CONTEXT *c;
    PJ *p;
    int errno;
    const char *errstr;

    c = proj_context_create();
    p = proj_create_crs_to_crs(c, "EPSG:4326", "EPSG:3857", NULL);

    if (p == 0) {
        /* Something is wrong, let's try to get details ... */
        errno = proj_context_errno(c);
        if (errno == 0) {
            /* This should be impossible. */
            fprintf(stderr, "Failed to create transformation, reason unknown.\n");
        } else {
            errstr = proj_context_errno_string(c, errno);
            fprintf(stderr, "Failed to create transformation: %s.\n", errstr);
        }
        proj_context_destroy(c);
        return 1;
    }

    /* transformation object is valid, do work ... */

    proj_destroy(p);
    proj_context_destroy(c);

    return 0;
}

```

--------------------------------

### Pipeline with No Steps

Source: https://proj.org/en/stable/operations/pipeline.html

A pipeline must contain at least one step. This example will result in an error.

```PROJ
+proj=pipeline
```
Tokens:
Raw