Thanks! Masking off the sky worked.
Masking the sky automatically would be great. Would it be possible to automatically mask areas of the images by color ranges? Because the sky is usually quite contrasting compared to trees and buildings.
Right now, I used the "Magic wand" tool. On small datasets, it's great. You have to click on all the sky areas but don't actually have to draw the mask yourself. But on larger datasets, this method would become quite time-consuming.
Kalev
It is definitely possible to automate masking the sky in other software (we personally use Photoshop to do this for 360 equirectangular images). We basically set up an action and do this:
1. Cut the top 50% of the image into a new layer (along the horizon) - this means anything that happens to have the same colour as the sky in the bottom of the image is not masked out)
2. Open up the layer styles dialogue and then adjust the blending option sliders on grey (since I am in Scotland!) or blue to remove the sky.
3. set the background of the image to be black and the front image to be white (black parts work as the mask).
4. Merge layers back together.
Unfortunately this relies on a lot of factors (images taken with a straight orientation i.e. no squint horizons, and a consistent sky in all of your images). there are probably better ways to do this, I am currently investigating myself! You can also use colour selection tool in Photoshop - however again this relies on you having a
very consistently coloured sky.
An addition in Photoscan to be able to do this would be hugely beneficial.. Even just a colour selection mask would be great. It would make Photoscan an all in one application for this process which would be incredible.
Will definitely have to try out the script.
Have a look at https://github.com/agisoft-llc/photoscan-scripts/blob/master/src/masking_by_color_dialog.py
P tried tjis script on your image set and it masks al the image!