Workflow for adding MTPs to both uncalibrated and calibrated images

PIX4Dmapper PIX4Dmapper Questions/Troubleshooting
1

Hi all,

I have to create/generate a orhofacade of a vertical surface, 2 upper rows of images taken with a drone and one row taken from ground with the drone held in hand. The building is very complex, with lot of glass and metal structures.

After the first step 1. Initial Processing there are a lot of uncalibrated cameras (44%), which you can see in the image:

As I cannot re-fly the mission again, I will have to somehow calibrate the images.

When trying to add MTPs to the uncalibrated images in the rayCloud editor, in the right pane there are only uncalibrated images listed. So how can I get  the calibrated images listed in the right pane? 

In the link https://support.pix4d.com/hc/en-us/articles/202560189-How-to-manually-calibrate-uncalibrated-Cameras-in-the-rayCloud it says that you click a red cross and try to link it to a point in a calibrated image. But in the section Images there are no calibrated images to link to.

If I select a point in the rayClod, then it gives me some calibrated and some uncalibrated images. But after adding MTPs and reoptimizing, the uncalibrated images stay uncalibrated.

So could someone write down the workflow/ exact steps how to add MTPs to a point in an uncalibrated image and to the same point in an calibrated image?

Best Regards. 

  

2

Hi Nada,

Could you provide us the quality report?
Which Matching Image Pairs are you using? For this kind of project I would recommend you to use “Free Flight or Terrestrial”: It could be to improve the calibration.

It is not surprising that you have many uncalibrated images since glassy building are uniform and reflective which make it difficult for the algorithm to find keypoints.

Have you correctly double clicked on a tie point? When you select a red tie point it turns into purple and then calibrated images are shown at the bottom of the sidebar:
TIP: you get an enlarged view of an image by clicking on the space bar. It makes much easier to select tie points.


Hope this will help.

3

Hi Marco,

I’ve tried all the different options for Matching image pairs, also all combinations of Custom in matching, but lastly the best result came from processing again with Free flight or corridor: 56% images came out calibrated. I would send the report, but it’s in PDF so I can’t attach it.

In the mean time I figured out how to calibrate the uncalibrated images, it’s a heavy manual job. Still not clear to me when the Calibrate button stops to be grayed out and when the crosses on the lower image turns pink or yellow. But I will figure that out also.

Do you think that I can get all images calibrated with this method, calibrating and adding MTPs?

Best regards

4

Hi Nada,

You can upload your quality report in this onedrive folder. Maybe having a look to your setting we could recommend you some set ups that could improve the calibration. 

Manual calibration is a painful and very time consuming method, but as the algorithm cannot get enough keypoints for the third flight I do not see many other alternatives.
However I doubt that you can get them all calibrated.

I can also suggest you to process the top flight separately and then merge the projects.

Best,