After shooting a map of a decent sized Church Building and lot there is a huge hole in the center of the map. I was planning on doing a sample roof report on this map but it’s got a huge hole in it. Looking back through the photos the entire roof including the areas in the “hole” are captured in several images. I am using a free trial to try to get some nice assets to use for marketing material and am limited on time and number of maps I can create.:
July 28, 2018:
DJI Phantom 4 Pro V2.0:
**Samsung Galaxy S7: Android version 8.0.0 **
DroneDeploy App Version: 2.77.0:
Can you provide more details about your map? What is the name of the map?
Keep us posted,
Hi Christina, the Map name is “Church”. I shot additional oblique images of the structure and figured out how to add additional images to the map. I was able to upload an additional 26 images and it is currently reprocessing. The additional images I uploaded are all of the area of the structure where the hole is. I am hoping there is more than enough additional data there to reconstruct a correct rendering of the structure.
How did it go? Can you share a link to the map?
Well, it’s better, but still has a big hole in the roof… I’m wondering if it was the reflective surface of the roof that caused a difference in color of the main section of roof that caused the mapping engine to just drop it… I’m also seeing some crappy stitched edges that a human would obviously see as being totally straight being constructed in sections that are jagged…Here is a link to the map:
Try to do another map but make your altitude greater than 200 ft. Higher is better. Your current 125 is pretty low for an ortho. Make your overlaps 80/80.
In addition to your mapping mission be sure to take perimeter shots from all sides. A lower altitude works for this but be sure there is no sky visible in your pictures. A camera angle of approx 45deg works good. Just figure out what radius you need for your chosen altitude to make it happen. (If you have a DJI drone the POI function works well for the exterior/perimeter photos.)
I hope you are doing well! @Garryowen feedback is very accurate. Usually flying higher and increasing overlap helps to provide more tie point that our algorithm can use to successfully stitch those repetitive patterns in the roof.
Additionally, and as you mentioned before, reflectivity is also problematic. Reflectivity causes specular highlights that change location between images, that makes more difficult for our stitching algorithm to find keypoints to correctly create your map. When you are mapping water or any other reflective surface, you might consider using a polarizing filter on your drone’s camera.
@Garryowen thanks again for sharing your insights with the forum community. Have a great day you both and happy mapping!