Reconstruction model error using Pix4D

[rbhikule]

Hi, I am new to Pix4D and using the trial version. We are trying to recreate a construction site where rebars are kept on the ground. I am getting a few errors and irregularities during the process.

1. Even when the images are overlapping enough, the images are still being showed uncalibrated (even if they have enough keypoints). What can be done to rectify this problem?
2. When the keypoint matching process takes place, incorrect keypoints are being matched which is resulting in ghosting(creating double models of one object with an offset) during the 3D reconstruction.
3. What can be done to improve the keypoint matching and decrease the reconstruction error? How do reduce the outliers (the ones which are not matching) in keypoints?

I am attaching the Quality Test report.
Test5_report.pdf (185.7 KB)

[Mike_K]

Hi rbhikule,
Thank you for attaching your quality report. I think the issue you have is that your image overlap is insufficient. Half of your cameras did not calibrate and you had two image blocks. The two blocks are why you are seeing a double model.

I would recommend not freeflying your project but rather use an automated flight app that will ensure your image overlap is consistent. I would program either a grid or cross-grid and keep your overlap between 70-85% percent. I would read the article below and always err with more overlap than less.

Image acquisition

[rbhikule]

Hi Mike

Thank you for replying.
I also tried with more overlap in the images. However, I am getting the same problem. There are two models getting reconstructed again.
I have attached the new generated report below.
Test4_report.pdf (251.9 KB)

[Mike_K]

Hi rbhikule,
Your overlap is simply insufficient. I still suggest a grid flight with constant overlap. The screenshot below should have dark lines connecting the images. Yours is light which indicates few keypoints were extracted. More overlap is required in order to correct this.