Asset Preparation
How to prepare drone, survey, and CAD source files for SiteCAD — and how to choose between local owned-tile bakes and geostore uploads for terrain, imagery, and 3D models.
Choosing an ingestion path
SiteCAD has two ways to bring source data into a site: owned-tile bake (browser parses the file and writes editable tiles on the active layer) and geostore upload (file goes to Cesium Ion via the backend; the layer references it as a base provider). Pick by aspect:
| Aspect | Owned-tile bake | Geostore upload | Recommendation |
|---|---|---|---|
| Terrain (DTM) | GeoTIFF bake — single-band elevation imported in-browser, stored as editable owned tiles. | Upload a higher-resolution Ion-hosted DTM as the layer base provider (no per-tile bake). | Owned-tile bake for sub-site rasters you intend to edit; geostore for survey-grade base coverage. |
| Imagery (Ortho) | GeoTIFF bake — 3- or 4-band orthomosaic baked into the layer’s owned imagery tiles. | Upload an orthomosaic asset as the layer’s imagery base provider. | Owned-tile bake is fastest for small areas; geostore for site-wide coverage. |
| 3D Model / Mesh | Not supported — meshes are never baked locally. | Upload OBJ, glTF/GLB, FBX, DAE, LAS/LAZ, KMZ, or CityGML; Ion processes into 3D Tiles. | Geostore is the only path. Provide a DTM first so the backend can strip ground triangles. |
All three aspects benefit when the layer’s terrain source is a bare-earth DTM. Imagery draping is sharper, cut/fill volumes match real grading work, and the backend uses the DTM to strip ground triangles out of uploaded photogrammetry meshes.
Terrain (DTM)
A digital terrain model represents the bare ground surface — no buildings, no canopy. SiteCAD accepts DTMs through both ingestion paths.
Accepted formats & constraints
.tif / .tiff (GeoTIFF)
Float32 / Int16 / UInt16 elevation; LZW or Deflate; tiled or stripped; COG OK.
CRS
Projected (UTM, State Plane) or geographic — reprojected to WGS84 via proj4.
Resolution
Site editing LOD targets ~1 m vertex spacing. Higher resolution is downsampled; lower resolution is bilinearly upsampled.
NoData
Pixels flagged NoData fall through to the base provider — no holes, but coverage gaps remain visible at lower layers.
Recommended export paths
WebODM
Set Processing Profile → "DTM". After processing, download odm_dem/dtm.tif from the task assets.
Agisoft Metashape
Workflow → Build DEM → Source data = Dense Cloud + Point classes = Ground → Export DEM as GeoTIFF.
Pix4D
Outputs → DTM. Export as GeoTIFF (.tif).
QGIS
For an existing DSM, run "Clip raster by mask" with a ground mask, or use the SAGA "DTM Filter" tool.
Imagery (Orthomosaic)
Orthomosaics are top-down, georeferenced color images of the site. They drape over terrain and provide ground truth for placement and grading.
Accepted formats & constraints
.tif / .tiff (GeoTIFF)
3-band RGB or 4-band RGBA. Tiled, stripped, or COG.
CRS
Any projected or geographic CRS; reprojected to WGS84 for tile alignment.
Alpha / nodata
Transparent pixels (alpha = 0 or all-nodata) are skipped during the bake.
Recommended export paths
WebODM
Default odm_orthophoto/odm_orthophoto.tif. 3-band by default; enable transparent background for 4-band.
Metashape
Workflow → Build Orthomosaic → Export as GeoTIFF, "Write tiled TIFF" enabled.
Pix4D
Outputs → DSM, Orthomosaic, and Index → Orthomosaic GeoTIFF.
3D Model / Mesh
3D models are the photogrammetry or LiDAR surface mesh — buildings, trees, ground, and surface detail. They render as a 3D Tileset over terrain and can be clipped per layer.
There is no owned-tile bake for meshes. All 3D models upload to the geostore. The backend samples the layer’s DTM at each vertex and removes ground triangles before tiling — if you skip the DTM, the mesh will sit on top of the terrain you already have rather than blending into your grading.
Accepted source formats
.obj
Wavefront OBJ + .mtl + textures. Bundle as a zip or use the directory upload.
.gltf / .glb
glTF 2.0 — preferred for single-file meshes with PBR materials.
.fbx
Common photogrammetry export from Metashape / RealityCapture.
.dae
COLLADA — accepted but glTF is preferred where available.
.las / .laz
Point clouds. LAZ is compressed LAS; both stream into 3D Tiles.
.kmz
KML zipped with referenced models. Useful for legacy datasets.
.citygml
CityGML LoD1–LoD3 building / city models.
3D Tiles directory
Pre-tiled output (tileset.json + tiles). Upload via "Upload Tileset…" in the Mesh inspector.
Recommended export paths
Metashape
Workflow → Build Mesh → Export Model → glTF (.glb) with textures.
RealityCapture
Export Model → glTF or OBJ + texture atlas.
WebODM
odm_texturing/odm_textured_model.obj + .mtl + .png files. Use "Upload Tileset…" for the whole directory.
Common pitfalls
Most failed uploads come down to one of these. Check them before re-running a long photogrammetry export.
Uploading a DSM instead of a DTM
Buildings and tree canopies appear as terrain. Brush edits work but cut/fill volumes will be wrong. The 3D-mesh ground-strip backend step also needs a DTM to classify ground vs. above-ground triangles correctly.
Missing CRS tags
A GeoTIFF without GeoKeys (ProjectedCSTypeGeoKey / GeographicTypeGeoKey) cannot be georeferenced. Re-export from your photogrammetry tool with CRS metadata enabled, or assign one in QGIS via gdal_edit.
Wrong band layout for imagery
SiteCAD reads bands 0–2 (RGB) or 0–3 (RGBA). A 1-band grayscale ortho or band order outside that range will look wrong; re-stack bands in QGIS or via gdal_translate -b 1 -b 2 -b 3.
Forgetting to bring textures with OBJ uploads
A single .obj file with no .mtl or .png alongside uploads as untextured grey geometry. Use "Upload Tileset…" and select the directory so the texture files come with it.
Hitting the geostore quota
Free tier allows ~500 MB / 5 uploads; Starter ~5 GB / 50; Pro ~50 GB / 500; Enterprise removes the cap. Delete unused assets in the Asset Library before uploading large drone runs.
Mesh upload before a DTM exists
Without a layer DTM, the backend ground-strip step has nothing to compare vertices against — the full photogrammetry mesh (buildings, trees, ground) renders on top of terrain. Always upload the DTM first.
End-to-end workflow
The full path from drone flight to a usable SiteCAD layer.
Capture
Drone photogrammetry (RGB + RTK if available) or terrestrial / aerial LiDAR.
Process
Run photogrammetry (WebODM, Metashape, Pix4D, RealityCapture) or LAS classification.
Export
Three outputs: bare-earth DTM (.tif), orthomosaic (.tif), and textured mesh (.glb / .obj). Verify CRS tags are present.
Choose ingestion path
Owned-tile bake from the Layer Panel for small editable rasters, or geostore upload from the Layer Editor for site-wide base providers and meshes.
Select in Layer Editor
Open the layer’s editor and pick the new asset for terrain, imagery, and 3D model rows. The layer takes effect immediately — brush, contours, and cut/fill recompute on the next interaction.