Show Posts
1
General / Nadir Photographs Aligning at Two Separate Elevations / Oblique Fine
« on: March 11, 2025, 07:27:19 PM »
Hello, and thank you ahead of time for the help.
We have a project that we flew approximately 60 photographs in a nadir camera orientation and 60 photographs with a 78 degree oblique camera orientation. We used PPK to control the camera location at the time of photograph capture and all camera positions where within 6 feet elevation of each other according to the PPK results.
After importing the photographs, converting the camera positions to California State Plane Zone 5 coordinates and importing the source position PPK control file, we aligned the photographs and this is where things got weird.
All of the oblique and a portion of the nadir (about 2/3) aligned to the same elevation as the PPK source, with a portion of the nadir (about 1/3) aligned at a much lower elevation (about 50 feet lower).
More details:
For the nadir flight the first two flight lines aligned at the same elevation as the PPK coordinates and the oblique aligned camera positions. This is the first 1 - 18 photographs. Photograph number 19 is at the turn to the third flight line and it is about halfway in elevation between photograph 18 position and photograph 20 position. After and including photograph 20 the remaining nadir photographs (20 - 57) are at an aligned elevation approximately 50 lower than the first 18 nadir and all the oblique camera positions.
If I process just the nadir by themselves, the weirdest thing happens, the nadir camera positions align to a coordinate position that is lower in elevation than the sparse point cloud point elevations. As if the UAV was flying upside down inside some tunnel and was capturing photographs above the UAV or on the "ceiling" of land above it. Which of course is not the case.
I am attaching two screen grabs, one showing the nadir and oblique aligned camera positions and one screen grab showing the nadir only camera positions. I am also attaching a reduced resolution aerial ortho mosaic I was able to complete using the oblique images.
I appreciate any help that you can offer. Thank you. I have never seen this behavior before.
We have a project that we flew approximately 60 photographs in a nadir camera orientation and 60 photographs with a 78 degree oblique camera orientation. We used PPK to control the camera location at the time of photograph capture and all camera positions where within 6 feet elevation of each other according to the PPK results.
After importing the photographs, converting the camera positions to California State Plane Zone 5 coordinates and importing the source position PPK control file, we aligned the photographs and this is where things got weird.
All of the oblique and a portion of the nadir (about 2/3) aligned to the same elevation as the PPK source, with a portion of the nadir (about 1/3) aligned at a much lower elevation (about 50 feet lower).
More details:
For the nadir flight the first two flight lines aligned at the same elevation as the PPK coordinates and the oblique aligned camera positions. This is the first 1 - 18 photographs. Photograph number 19 is at the turn to the third flight line and it is about halfway in elevation between photograph 18 position and photograph 20 position. After and including photograph 20 the remaining nadir photographs (20 - 57) are at an aligned elevation approximately 50 lower than the first 18 nadir and all the oblique camera positions.
If I process just the nadir by themselves, the weirdest thing happens, the nadir camera positions align to a coordinate position that is lower in elevation than the sparse point cloud point elevations. As if the UAV was flying upside down inside some tunnel and was capturing photographs above the UAV or on the "ceiling" of land above it. Which of course is not the case.
I am attaching two screen grabs, one showing the nadir and oblique aligned camera positions and one screen grab showing the nadir only camera positions. I am also attaching a reduced resolution aerial ortho mosaic I was able to complete using the oblique images.
I appreciate any help that you can offer. Thank you. I have never seen this behavior before.
