An orthophoto is an orthorectified (meaning that distortions affecting other aerial imagery have been removed) top-down photograph, in this case of the model of a context. Orthophotos can be mosaiced into orthomosaics, but in KAP terminology, we use the simpler term. Orthophotos are used by the excavators to draw illustrations of stones, in situ ceramics, features, etc. in Day Plans. These illustrations will later be used to create plans for reports and publications, so it is important that the orthophoto is accurate and comprehensible.
Orthophoto Workflow #
- To create the orthophoto, go to Workflow>Build Orthomosaic.
- All settings should be at the default:
- Ensure the Type is Geographic
- You may want to change the pixel size to reduce the size of the file and the time it takes to load. It is best to leave the pixel size at its defaults for small contexts, but for very large contexts, you may want to increase the pixel size to c. 0.001–0.005, depending on the size of the context. It is important that the excavators are able to see the detail in the orthophoto, so consider that when choosing a pixel size.
- If you build an orthomosaic for a model in which overhanging material has been clipped out, you should also disable the cameras that capture the overhang before building the orthomosaic. Otherwise, the image of the overhanging material might be projected onto the clipped model below.
- To export the orthophoto you created above, go to File> Export> Export Orthomosaic> Export TIFF
- Use the following settings:
- Unlike other products of the photobatch processing workflow, you will not save the orthophoto in the photobatch folder. Instead, you will save it in a folder with the DEMs and other materials for GIS work.
- File path: E:\gygaia\gisgps\kap\[year]\rasters\photoscan_exports\[EA]
- File name: P[photobatch number] (e.g., P201905241242)
- Double-check 1) that you are saving the orthophoto under the correct year and the correct excavation area and 2) that you use the correct file prefix (in this case, P), or it will be difficult for the excavators to find what they need to draw their day plans.
- Now you can continue to the next step in the workflow.