JPG compression settings for 42 MP camera

PIX4Dcapture PIX4Dcapture Questions/Troubleshooting
1

We’re using a 42 MP camera (Sony RXIR II) for image acquisition. The resulting images are obviously pretty large and processing times are tremendous. I’m searching for a good balance between result quality and processing times.

  1. Would you recommend using normal, fine or extra fine image compression (JPG)? How is the result quality and the processing time typically affected by the different compression rates?

  2. To speed up the process I’m considering changing the camera settings from 42 MP to 18 MP and use extra fine compression. Do I have to expect a huge quality loss of the results, or does it only affect the GSD?

2

I think the best would be to setup an experiment for the use case you are working most often with. 

For example, do three projects of the same area and having only the parameter of the image compression vary between the projects. This will enable you to see if you still get enough accuracy based on your use case.

I would be cautious about: 

  • camera model in the software: changing the compression rate results in different resolutions of images for the same camera parameters (sensor width, lens,…). In my opinion, it would be necessary to create a new calibrated camera model for each of the different compression rates: https://support.pix4d.com/hc/en-us/articles/206065716

  • another way to reduce the processing time, would be to change the scale at which the keypoints are extracted and at which the densification of the point cloud is done. This would ensure that you do not have to modify the camera model or the compression rate. Here is an example for step 1: 
    This approach seems safer to me. 

Hope it helps!

3

I am running into a similar question with a 45MP camera (Nikon D850). What compression type did you end up using on this project? Did you see a significant difference in processing time and/or output quality with different compression levels?

 

Any help would be greatly appreciated!