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

Hi Benjamin,

sorry I wasn't clear, I mean the whole dgn file, before export to LumenRT Connect Edition Up 1.
Because there is a know defect regarding files greater than 2GB .

if it is not the case, please sent us the file in order to test in our environment

regards
Mara

Mara,

All of the information, both in the original file and references, is only 155 MB total. I have uploaded a zip file containing the original file (Modeling_BAP.dgn), the image draped surface (pa0206_NoVoids_Descartes.dgn) and some other ancillary references to the Bentley secure upload system. Let me know if you need anything else.

Thanks,

Benjamin

Hi Benjamin,

The full resolution aerial images are not taken across from LumenRT. Here is what happens depending on the type of terrain used:

1. If using a MicroStation Terrain Model, the aerial maps are composited into a 1K x 1K image (V8i) or 4K x 4K image (Microstation Connect Edition)
2. If using a Descartes STM (this is your case), the images are broken up into 512 x 512 or 1024 x 1024 tiles depending on the resolution of the terrain – moving closer to the terrain with the camera will generate larger image tiles.
3. If using a RealityMesh for the terrain, these are tiled at 512 x 512

I hope this explains

regards
Mara

Hi Mara,

What's not clear from your explanation is the actual size of the tiles being compared.

If I had a 1km x 1km draped mesh, with the draped image being 8000pix x 8000pix, are you saying that V8i would resample the single image down to 1000pix x 1000pix - or create 8 tiles of 1000pix x 1000pix each?

Similarly, would CE more efficiently create two tiles of 4000pix x 4000pix?

Essentially, which is the best method to create the highest resolution? From your notes it looks like;

Best = Connect Edition draped mesh
Next best = V8i mesh draped mesh
No too good = Descartes STM & Reality mesh.

Also, what is the purpose of "large model LumenRT export" relative to the standard export? Does it control resolution output, or fidelity of imported geometry?

Max

Hi Mara,

What's not clear from your explanation is the actual size of the tiles being compared.

If I had a 1km x 1km draped mesh, with the draped image being 8000pix x 8000pix, are you saying that V8i would resample the single image down to 1000pix x 1000pix - or create 8 tiles of 1000pix x 1000pix each?

Similarly, would CE more efficiently create two tiles of 4000pix x 4000pix?

Essentially, which is the best method to create the highest resolution? From your notes it looks like;

Best = Connect Edition draped mesh
Next best = V8i mesh draped mesh
No too good = Descartes STM & Reality mesh.

Also, what is the purpose of "large model LumenRT export" relative to the standard export? Does it control resolution output, or fidelity of imported geometry?

Max

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.

Thanks Dave, useful insights as always,

Max