Unity Package for GDAL

The Geospatial Data Abstraction Layer (GDAL) is a translator library for raster and vector geospatial data formats that is released under an X/MIT style Open Source License by the Open Source Geospatial Foundation. It provides a single data model for multiple supported data formats.

This repo is a Unity Package for using GDAL in a Unity project.

This Package is part of the ViRGiS project - bringing GiS to VR.

Installation

The Package can be installed from Open UPM. If you use this method, the dependencies will be automatically loaded provided the relevent scoped registry is included in your project's manifest.json :

scopedRegistries": [
    {
      "name": "package.openupm.com",
      "url": "https://package.openupm.com",
      "scopes": [
        "com.openupm",
        "com.virgis"
      ]
    }
  ],

The Package can also be installed using the Unity Package Manager directly from the GitHub Repo.

Build Tests and Platform Support

This package is build-tested on multiple platforms using the ViRGiS Team Test Project.

See that project for working examples and the current list of working platforms.

Version numbers

UPDATED NOTE ABOUT VERSIONS:

This OpenUPM package wraps a Conda Package that invokes GDAL.

Because of the way that Conda works as a package manager, this means that the actual library version is actually determined by the Conda version algorithm which is dependent on platform and on what other packages are loaded. The version pin is "x.x" which means that, if the package version is "3.4.xx" (e.g. 3.4.100) then the actual version loaded is most recent version in the range 3.4.00a0 to 3.5.00a0 - which at the time of writing would be 3.4.3!

Therefore, the OpenUPM package number is done as follows x.y.b where x.y MAJOR & MINOR versions of GDAL to which this package is pinned and b is the build number of the package (starting e.g at 3.5.0 to mean build 0 of the package for GDAL 3.5.x and going up incrementally).

Also note that this evaluation is only done when downloading GDAL. There is currently no function to update GDAL - the only way is to delete the Conda folder (and Conda.meta ) WHEN Unity is closed.

A note about Upgrading

Unity is a bit "graby" about DLLs and SOs. Once it is loaded it keeps a hardlink to the DLL and does not like changing. This means that for this package, once you have upgraded to a new version of the UPM package you will, usually, need to restart the Unity Editor for the change to work.

Development and Use in the player

NOTE For the avoidance of doubt, Conda is NOT required when the application is deployed as a Unity application. All required libraries are automatically included in the distribution package created by Unity.

The scripts for accessing GDAL/OGR functions are included in the OSGEOnamespace and follow the GDAL/OGR C# Api.

The GDAL library is loaded as an unmanaged native plugin. This plugin will load correctly in the player when built. See below for a note about use in the Editor.

All versions of this package work in all supported architectures using the Mono scripting back end. As of package version 3.4.102, the package will succesfully build using the IL2CPP scripting backend. The package does NOT support the .NET scripting backend in the UWP player since that scripting backend does not support the System.Runtime.InteropServices namespace.

Architecture	Mono	IL2CPP	.NET
Windows Standalone	Yes	Yes	--
MacOS Standalone	Yes	Yes	--
Linux Standalone	Yes	Yes	--
UWP (see note 1)	--	Yes	No
Android	Not Yet	Not Yet	--
iOS	Not Yet	Not Yet	--
WebGL.	Never	Never	--

NOTE 1 - The UWP architecture has currently only been tested as far as a successful build and not as far as deploying an application - since I do not have the time or resources to do that. If you have successfully deployed an app then please raise an issue to say so. Thanks.

NOTE 2 - The package architecture should, in principle, be able to support Android and iOS architectures in the future but this has not been implemented. Yet.

NOTE 3 - the package architecture will never be able to support the WebGL player - since it relies on native dlls.

Running in the Editor

This package uses Conda to download the latest version of GDAL.

As of version 3.11.1, this package uses Version 2 of the Conda Extension package. This means that the package now includes a complete self contained and standalone installation of the Conda API. You no longer need to install Conda on your development machines.

Note that when upgrading, you MUST delete the Assets/Conda directory and restart Unity.

Initialising GDAL

This package installs the GDAL package, which copies data for GDAL and for PROJ into the Assets/StreamingAssetsfolder. You may also want to exclude this folder from source control.

GDAL needs to be told where to find the proj data package,

To do this, the package includes a version of the GdalConfiguration.cs script (see https://github.com/ViRGIS-Team/gdal-upm/blob/main/Runtime/Scripts/GdalConfiguration.cs)

A minimum program would look like:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using OSGeo;


public class test : MonoBehaviour
{
    void Start()
    {
        GdalConfiguration.ConfigureGdal();
    }
}

Documentation

See the GDAL/OGR C# Api.

Unity Extensions

This package includes some extensions to the API for Unity and for ViRGiS Geometry:

• Band has the addition of Band.ToMesh() that converts the Band into a VirgisGeometry.DMesh3 mesh, assuming that the band values are elevation,
• Band has the addition of Band.ToArray() that converts the Band into a double[],
• Dataset has the addition of Dataset.ToRGB() that attempts to convert a dataset into a Texture2D assuming that the Dataset has r,g and b bands with reasonable names,
• Utilities to project DMesh3 and DCurev3 using OSR, using the ViRGiS Geometry AxisOrder utilities to allow projection into the Unity left-handed coordinate space.

Minimum Project / Test Project

You can see a minimum working project in the test project used to test build this package (and two others):

https://github.com/ViRGIS-Team/test-project.

Use with Unity Cloud Build

As of release 3.11.1 this package will work with Unity Cloud Build without any additional work or pre-build scripts.

Uniy Cloud Build extensively utilises macOS on Apple Silicon as its runners. To build for osx-64, you need to have a separate build and override the Conda architecture by creating the following environment variable in the Unity Cloud Build configuration (or similar for different build hosts) :

Name	Value
CONDA_ARCH_OVERRIDE	osx-64