How do I place a 3D model on the map?¶
osgEarth::GeoTransformclass inherits from
osg::Transformand will convert map coordinates into OSG world coordinates for you. Place an object at a geospatial position like this:GeoTransform* xform = new GeoTransform(); GeoPoint point(srs, -121.0, 34.0, 1000.0); xform->setPosition(point);
If you want your object to automatically clamp to the terrain surface, assign a terrain and leave off the altitude:GeoTransform* xform = new GeoTransform(); xform->setTerrain(mapNode->getTerrain()); GeoPoint point(srs, -121.0, 34.0); xform->setPosition(point);
I loaded a model, but it has no texture/lighting/etc. in osgEarth. Why?¶
Everything under an osgEarth scene graph is rendered with shaders. So, when using your own models (or creating geometry by hand) you need to create shader components in order for them to render properly.
osgEarth has a built-in shader generator for this purpose. Run the shader generator on your node like so:osgEarth::Registry::shaderGenerator().run( myNode );
After that, your node will contain shader snippets that allows osgEarth to render it properly and for it to work with other osgEarth features like sky lighting.
Lines or Annotations (FeatureNode, etc.) are not rendering. Why?¶
Lines render using a shader that requires some initial state to be set. You can apply this state to your top-level camera (or anywhere else above the geometry) like so:#include <osgEarth/GLUtils> … GLUtils::setGlobalDefaults(camera->getOrCreateStateSet());
For Annotations (FeatureNodes, PlaceNodes, etc.) best practice is to place an Annotation node as a descendant of the MapNode in your scene graph. You can also add them to an AnnotationLayer and add that layer to the Map.
Annotations need access to the MapNode in order to render properly. If you cannot place them under the MapNode, you will have to manually install a few things to make them work:#include <osgEarth/CullingUtils> #include <osgEarth/GLUtils> ... // Manully assign the MapNode to your annotation annotationNode->setMapNode(mapNode); // In some group above the annotation, install this callback group->addCullCallback(new InstallViewportSizeUniform()); // In some group above the annotation, set the GL defaults GLUtils::setGlobalDefaults(group->getOrCreateStateSet());
Again: MapNode does all this automatically so this is only necessary if you do not place your annotations as descendants of the MapNode.
How do make the terrain transparent?¶
By default, the globe will be opaque white when there are no image layers, or when all the image layers have their opacities set to zero. To make the underlying globe transparent, set the base color of the terrain to a transparent color like so:<map> <options> <terrain color="#ffffff00" ...
In code, this option is found in the
RexTerrainEngineOptionsclass:#include <osgEarthDrivers/engine_mp/RexTerrainEngineOptions> using namespace osgEarth::Drivers::RexTerrainEngine; ... RexTerrainEngineOptions options; options.color() = osg::Vec4(1,1,1,0);
How do I set the resolution of terrain tiles?¶
Each tile is a grid of vertices. The number of vertices can vary depending on source data and settings. By default (when you have no elevation data) it is an 17x17 grid, tessellated into triangles.
You can expressly set the terrain’s tile size by using the Map options. osgEarth will then resample all elevation data to the size you specify. You will get best results from a tile size that is a power of 2 plus 1:<map> <options> <terrain> <tile_size>9</tile_size> ...
Other Terrain Formats¶
Does osgEarth work with VirtualPlanetBuilder?¶
VirtualPlanetBuilder (VPB) is a command-line terrain generation tool. Before osgEarth came along, VPB was probably the most-used open source tool for building terrains for OSG appliations. We mention is here because many people ask questions about loading VPB models or transitioning from VPB to osgEarth.
osgEarth differs from VPB in that:
- VPB builds static terrain models and saves them to disk. osgEarth generates terrain on demand as your application runs; you do not (and cannot) save a model to disk.
- Changing a VPB terrain generally requires that you rebuild the model. osgEarth does not require a preprocessing step since it builds the terrain at run time.
- osgEarth and VPB both use GDAL to read many types of imagery and elevation data from the local file system. osgEarth also supports network-based data sources through its plug-in framework.
osgEarth has a VPB driver for “scraping” elevation and imagery tiles from a VPB model.
Confiugration of this driver is quite tricky and requires you to understand the details of how VPB models are organized. You’re on your own.Please Note that this driver only exists as a last resort for people that have a VPB model but no longer have access to the source data from which it was built. If at all possible you should feed your source data directly into osgEarth instead of using the VPB driver.
Can osgEarth load TerraPage or MetaFlight?¶
osgEarth cannot load TerraPage (TXP) or MetaFlight. However, osgEarth does have a “bring your own terrain” plugin that allows you to load an external model and use it as your terrain. The caveat is that since osgEarth doesn’t know anything about your terrain model, you will not be able to use some of the features of osgEarth (like being able to add or remove layers).
For usage formation, please refer to the
byo.earthexample in the repo.
Community and Support¶
What is the best practice for using GitHub?¶
The best way to work with the osgEarth repository is to make your own clone on GitHub and to work from that clone. Why not work directly against the main repository? You can, but if you need to make changes, bug fixes, etc., you will need your own clone in order to issue Pull Requests.
- Create your own GitHub account and log in.
- Clone the osgEarth repo.
- Work from your clone. Sync it to the main repository periodically to get the latest changes.
How do I submit changes to osgEarth?¶
We accept contributions and bug fixes through GitHub’s Pull Request mechanism.
First you need your own GitHub account and a fork of the repo (see above). Next, follow these guidelines:
- Create a branch in which to make your changes.
- Make the change.
- Issue a pull request against the main osgEarth repository.
- We will review the PR for inclusion.
If we decide NOT to include your submission, you can still keep it in your cloned repository and use it yourself. Doing so maintains compliance with the osgEarth license since your changes are still available to the public - even if they are not merged into the master repository.
Can I hire someone to help me with osgEarth?¶
Of course! We at Pelican Mapping are in the business of supporting users of the osgEarth SDK and are available for contracting, training, and integration services. The easiest way to get in touch with us is through our web site contact form.
Pelican also offers a Priority Support package that is a good fit for companies that prefer to do most of their development in-house.
Can I use osgEarth in a commercial product?¶
Yes. The license permits use in a commercial product. The only requirement is that any changes you make to the actual osgEarth library itself be made available under the same license as osgEarth. You do not need to make other parts of your application public.
Can I use osgEarth in an iOS app?¶
Yes. Apple’s policy requires only statically linked libraries. Technically, the LGPL does not support static linking, but we grant an exception in this case.