Build Voxel World Tutorial - ngageoint/voxel-globe GitHub Wiki

Once a dataset has been registered, the dataset is ready for voxel world processing. In the case of the Providence data used in the tutorial, the cameras are already registered.

To start, click "Build Voxel World" to begin an order. Select the Image Set, Camera Set, and Scene to use.

For georegistered models, a Cesium interface will appear on the right. See here for the unregistered case.

images/build_voxel_world_geo.png

Once you have selected the origin, the next page will show pre-calculated bounding box. The bounding box defines the boundaries of the scene containing all the voxels. During SFM processing, matching tie points are stored for every feature matched between multiple images. These tie points are used to determine the location and size of a bounding box including most of the tie points while excluding outliers. This bounding box is stored for use in this Voxel World application. In non-SFM cases, it can be loaded from ingest_voxel_globe.json.

You can click on the black spheres to easily position the voxel world latitude and longitude boundaries. Click and drag the ▲▼ icons to adjust the top and bottom boundaries. The bounding box can also be entered manually on the left.

  • The top set of coordinates represent the latitude, longitude, and altitude of the world.
  • The bottom set of coordinates represent the same thing, but in a local coordinate from in meters. It is often easier to enter the information in one form or the other. They instantly update together.

Using some a priori knowledge, you can change any of the values and update the bounding box estimates. For example, you could choose to have the bounding box go between 100m to -60m.

Next, set the voxel size to approximate GSD.

The defaults will work for Providence

  • South - -300 meters
  • West - -250 meters
  • Bottom - -100 meters
  • North - 500 meters
  • East - 450 meters
  • Top - 100 meters
  • Voxel Size - 0.5 meters

After selecting your bounding box, click submit and the processing will begin. First, the images are copied from the Image server to the Processing server, next each image is processed for the update cycle. There are a total of 5 update cycles, with a refine between each update, followed by a final color update. Once the processing is complete, and the database is updated with a new voxel world.

To preview the newly generated voxel world, see the point cloud, then the point cloud viewer can be used.