What's the best way to merge orthophoto tiles from Contextcapture into a single large geotiff image with BCCEditor?
For most jobs I attach the raster image tiles into the editor and use the merge function, however the program always freezes when attaching the images.
Freeze time can vary between a few minutes to a couple of hours depending on the size of the job. And some larger jobs crash altogether.
I've also tried attaching the 3MX file instead and using the merge function to deliver an orthophoto that way but it often has white squares missing from it and the quality is much lower than using raster image tiles.
Any solutions would be greatly appreciated.
There are multiple issues(Defect Report 67694, Enhancement Request 638691) related to Raster attachments in Editor/Microstation so no workflow possible.
Basically what I found out that there is issues with local cache generation. First it loads in RAM (by default up to 25% is used) and then tries to create raster cache(.ctiff) under temp even that such would not be needed for uncompressed tiff. When reserved RAM runs out then it switches to cache and that cause freeze and other issues because cache gets corrupted somehow. What I found out that if set to use RAM only(Preferences->Raster) then there are no issues with merge but need lot of RAM to complete. So need at least 32-64GB depending on size.
Alternative is using GDAL to merge rasters it works flawlessly. Seesm we are in the age were proprietary software are lacking behind opensource.
Also in latest Contextcapture there is a option to merge orthophoto parts which actually uses GDAL behind the scenes to merge these so it has no issues as Editor. What is desperately needed is some more optimized format for merging large rasters like ECW and I am glad that finally it is being considered.
Cameron said:I've also tried attaching the 3MX file instead and using the merge function to deliver an orthophoto that way but it often has white squares
This is also an outstanding issue reported multiple times without any fix. It is not issue actually with merge but with Microstation engine as in larger zoom levels some 3mx tiles are not displayed. Workaround is to use 3sm format. Have no hopes that it will be fixed in timely manner so we are stuck with workaround.
Thanks for the reply Oto. I'll look into GDAL tomorrow.
Using the 3SM format will be a last resort for me as the "3D mesh to orthophoto" process using 3sm or 3mx has some similar freezing and RAM issues as well. The final image quality is quite poor compared to raster images also.
I had tried increasing the RAM allowed or using RAM only but I think some of my projects are too large. Computers with 128GB and 256GB of RAM have both had the same issues. Most of the time I just attach the images in smaller groups and wait for the program to unfreeze, which isn't ideal but has been the only way so far.
Cameron said:Computers with 128GB and 256GB of RAM have both had the same issues
Yes because 64bit software doesn't mean it can use all RAM optimally.
You need to use GDAL buildvrt and then convert.
Why do you create orthophoto from mesh and not in Contextcapture?
I create orthophotos in Contextcapture Master but it makes tiles that are 4096x4096 pixels so I need to merge them in the editor. Small jobs have 20-40 or so tiles but the larger ones have hundreds of tiles. More tiles just take longer to attach and merge without crashing. Larger tiles don't work/fail production.
I've only used the 3d mesh to create an orthophoto on occasions when the raster images tiles have repeatedly failed to attach and merge in the editor. Strangely it's the 3d mesh method that Bentley present at industry events and demos as the way to create an orthophoto rather than the orthophoto tiles from CC Master.
Latest Contextcapture U19 has option to "merge othophoto parts" and also merge OBJ in one LOD.
You can increase tiles sizes but also around 10000x10000 it starts to fail. For larger TIFFs there is a BigTIFF standard which again makes all more confusing.