How to Merge a high resolution (ground) and a "10cm" (aerial) model

Background

User has a requirement to merge photos taken from different sources i.e. Dataset has been aquired  from images taken using a DSLRr & Drone Camera

Steps to Accomplish

Aerotriangulation

• Process a “standard” AT on the high-res (ground) dataset
• On this Aerotriangulated block, open the Tie-points editor
• Identify points of interest that can also be viewed in the “10cm” (aerial) model and click them in at least two photos to get their estimated coordinates. Save this values in a GCP import file.
• Open the 10cm Aerotriangulated block
• Open the ControlPoints editor
• Add the freshly identified points and their coordinates in the GCP tab
• Point them in some “10cm” images and save
• Run an AT on the “10cm” block using these GCP for adjustment
• Your two blocks (high-res and “10cm”) are now correctly georeferenced and ready for merging step

Merging blocks

• Select your two blocks in the project column > Right click > Merge

Reconstruction

• Create two Reconstructions
• The most important thing here is the tiling. As you have different resolutions, you will probably have to produce in  different size of tiles
• In the first one (Reconstruction 1), you will only produce tiles based on aerial imagery, so set a tile size according to this dataset
• Produce only the tiles that surround the area of interest (covered by the ground imagery)
• In the second reconstruction (Reconstruction 2)
• Set the exact same tiling SRS as for Reconstruction 1
• Set the exact same tiling origin as for Reconstruction 1
• Set a tile size which is a multiple value of Reconstruction 1 tiles (e.g.: if Reconstruction 1 has 160m tiles , then set it on 160m or 80m, 40m, 20m,… regarding to your data and to your computer resources)
• Produce the tiles which cover the area of interest and the surrounding ones to extend the production to a Reconstruction 1 tile

• On the image above:

- Blue: Area covered by aerial imagery
- Black: Tiling of Reconstruction 1
- Red: High-res model area of interest
- Yellow: Bounding box of your Production 2 area.
- White: Smaller tiles you must produce

• On top of that, you must also take care of producing Production 1 and Production 2 in the exact same SRS (same SRS and same origin in the Production settings)
• Once your two productions are complete, use the S3C-Scene-Composer to merge them.