Aerial Imagery in LumenRT

Hi,

what's the size or your file? greater than 2GB?

regards
Mara

The .lrt file ends up being about 0.5 GB raw from Microstation. The image that is being draped is relatively small, and is only 8 MB.

-Ben

Mara,

I am still somewhat confused.

Why does small model export versus large model export handle the exact same draped image differently? Why is the small model export properly shown with bright colored aerial image pixels but the large model export black? It looks like a software bug.

Are you suggesting that if I split up a high resolution image into a bunch of smaller image tiles, LumenRT will successfully show the drape at full resolution in either large or small model export?

-Ben

Hi Max,

The downsampling of images draped on meshes during export is a function of the type of terrain mesh being used and whether or not you are using V8i or Connect.

Let's say I had aerial imagery consisting of 8 images I draped onto the terrain:

1). For standard Terrain Models (TM) found in basic MS and things like InRoads, even if you used multiple 8k x 8k images draped on the terrain, the output to LumenRT would be downsampled to s ingle 1k x 1k (V8i) or a single 4k x 4k image (MS Connect)

2). For Descartes Scaleable Terrain Models (STM), the 8 draped images would be turned into mesh tiles depending on how close or far away from the camera the STM is. At a medium range distance, you would get something like 8 tiles each having 512 x 512 resolution, so this would be higher effective resolution than regular Terrain Model (TM) output.

3). The highest possible resolution would be the new Reality Meshes. These basically output 512 x 512 or 1024 x 1024 images for all the tiles with each mesh tile being quite small. Also, in LumenRT Update 2 (later this month) you will be able to use the scaleable reality meshes meaning that there is no fixed resolution -- it will use all of the input maps resolution depending on how close the camera is to the mesh.

LumenRT Large Model Export is a V8i-only export facility to accommodate 32-bit operation on large models to prevent crashing. It basically does a 2 stage export so it's slower but more reliable than standard export. It has no bearing on the output resolution of image/aerial maps.

Thanks Dave, useful insights as always,

Max

David,

That would stand to reason that if separate exports to small and large models from the same file completed successfully, the output of both exports would be the same. As shown in the images above, the aerial images and model objects come in differently. The large model export does a better job with the 3d shapes, but shows aerial as black whereas the small model export shows the aerial image correctly but makes the objects render improperly if you zoom in too close.

What do you think could be the cause of this?

Thanks,
Ben

David,

That would stand to reason that if separate exports to small and large models from the same file completed successfully, the output of both exports would be the same. As shown in the images above, the aerial images and model objects come in differently. The large model export does a better job with the 3d shapes, but shows aerial as black whereas the small model export shows the aerial image correctly but makes the objects render improperly if you zoom in too close.

What do you think could be the cause of this?

Thanks,
Ben

Hi Ben,

It is probably a bug on the large model export facility in V8i causing this. Can you send me a PZIP of the file and the associated images and I will get someone to look at this. Send me a link to the file to david.burdick@bentley.com