How do I add autogen to Prepar3D photo scenery?

To add autogen buildings and trees to Prepar3D photo scenery, annotate the compiled photo BGL with the Autogen Annotator supplied in the matching Prepar3D SDK. Draw building footprints and vegetation polygons, assign standard autogen classes, save the generated .agn files in the add-on’s texture folder, then enable that scenery package in Prepar3D.

What do I need before adding autogen?

You need a working, geographically positioned photo-terrain BGL, the Autogen Annotator from the SDK matching your Prepar3D installation, and a writable scenery package with scenery and texture folders.

Autogen Annotator is a scenery-authoring utility, not an option inside Prepar3D. If the imagery is not yet working in the simulator, first check the process for installing the orthophoto layer and registering it in Prepar3D. If you have only source imagery rather than a compiled BGL, you must first compile and package the underlying custom scenery.

• Photo terrain: The imagery must already display in the correct geographical position.
• Matching SDK: Use the SDK intended for your Prepar3D release; mixing major versions can produce tool or configuration problems.
• Standard autogen definitions: Stock building and vegetation classes are the safest choice because Prepar3D already knows how to render them.
• A backup: Work on a copy, especially when annotating somebody else’s photo package.

The normal package arrangement is:

• My Photo Area/scenery/photo-area.bgl
• My Photo Area/texture/*.agn

The .agn files belong in the package’s texture folder, not its scenery folder. Their generated filenames identify geographical terrain cells, so do not rename them to match the photo BGL.

If a download already supplies matching .agn files, you do not need to redraw the autogen. Back up the package, preserve the filenames, and copy the files into the texture folder belonging to the intended photo scenery. An annotation set made for different imagery or coverage may place objects in the wrong positions.

How do I create buildings and trees with Annotator?

Create the annotations by loading the exact photo BGL used in Prepar3D, drawing footprints over its imagery and saving the resulting AGN terrain cells into the package’s texture folder.

1. Prepare the package. Close Prepar3D and copy the scenery to a writable add-on location outside the simulator’s protected core folders. Confirm that the BGL and empty texture folder have the structure shown above.
2. Open the photo BGL. Start Autogen Annotator from the matching SDK and load the compiled photo-terrain BGL. The tool should display the georeferenced imagery. A blank or wrongly positioned view usually indicates an unsuitable BGL, bad source georeferencing or an SDK mismatch.
3. Draw building footprints. Place building rectangles over ordinary structures, align them with the roofs and select an appropriate stock building class. Use several simple footprints for a block rather than trying to reproduce a complex landmark with generic autogen. Keep buildings off roads, aprons and runways.
4. Draw vegetation regions. Trace polygons around woodland, hedges or groups of trees, then assign a suitable stock vegetation class. A polygon defines an area in which Prepar3D generates vegetation; it does not preserve the position of every tree visible in the photograph. Cut around roads, water, buildings and cleared airport surfaces.
5. Save the annotations. Save regularly and confirm that the tool creates one or more geographically named .agn files. Place those files in the photo package’s texture folder without changing their names.
6. Activate and test the scenery. Register the package through the activation method supported by your Prepar3D version, then set both Autogen Building Density and Autogen Vegetation Density above their off or minimum positions. Restart Prepar3D after replacing annotation files so that cached terrain and autogen are reloaded.

Packages containing several photo BGLs may require annotation across each section of the coverage. Check tile boundaries carefully so that you neither leave empty strips nor create overlapping buildings and vegetation.

Stock classes avoid another common failure. Custom buildings, vegetation or regional classes require matching autogen description entries, often identified by GUID. Never overwrite Prepar3D’s global autogen-description files wholesale: a bad replacement can remove autogen from unrelated add-ons, while an annotation referencing an unavailable definition may display nothing.

Why is my autogen missing in Prepar3D?

Missing autogen is usually caused by AGN files in the wrong folder, disabled density settings, annotations made for different imagery, or another scenery layer excluding the objects.

Photo terrain does not automatically inherit all the stock landclass autogen beneath it. If the photo package has no matching annotation files, bare imagery is normally the expected result.

For exclusions, scenery-layer conflicts and missing annotation checks beyond the package itself, follow our systematic checks for missing Prepar3D buildings and autogen.

When should I use placed objects instead of autogen?

Use placed scenery objects for landmarks and exact geometry; use autogen for ordinary buildings and broad vegetation coverage.

A practical photo-scenery package normally combines the methods: vegetation polygons and generic buildings provide coverage, while individually placed objects represent airports and landmarks that autogen cannot reproduce accurately.