Annotate Mask/Global Mask

PIX4Dmapper PIX4Dmapper Questions/Troubleshooting
1

Hello,

 

I have followed the instructions for Annotate: Mask/Global mask (https://support.pix4d.com/hc/en-us/articles/202560549-How-to-Annotate-Images-in-the-rayCloud?flash_digest=51f5246b2abaeb434f1ffab4b099f61cb52654b3)

But I still have a couple questions. If for some reason the mask is no longer needed, is there a way to remove it? 

For example on a specific image I created a Global Mask, but after running steps 2/3 again it appears that the Global Mask applied is not giving the desired results. So I would like to remove the mask from the project. However when I go to the image that has the mask applied I can no longer see the mask. I can see the pencil next to the image name under the Properties/Selection, but I can’t see the mask. 

 

 

I’m trying to remove the banding in the following image. When looking at individual images it appears that they are over exposed in the lower right corner of the image. I was hoping to use a global mask to remove that part of the image in hopes of removing the banding. However after applying the Global Mask it does not seem to make a difference. 

Any suggestions on how to rectify the banding on this data set? I understand changing the camera properties and perhaps the flight plan could prevent this from happening. However we don’t have the opportunity to fly this particular area again.

 

Thank you in advance

2

Hello Ramiro,

you can deselect the usage of annotations for processing in the Processing Options, in the  Point   Cloud and Mesh > Advanced  tab as shown in the image below.

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After this box has been unchecked, process Step 2 again, to save the changes.

Regarding the banding effect, the stripes you see in your orthomosaic are most of the time due to multicopter drones that either face the sun in one line and turn its back to it on the way back. In such a case the angle to the sun changes. Since the stripes are in the direction of the flight, it might be that the stripes could also be due to vignetting of the original images. The effect of the vignetting can be reduced when there is high overlap, but this means flying again. The side overlap is, in general, lower than the frontal overlap and this is why the stripes are more visible in the direction of the flight. 

The vignetting is further improved during step 3 when the color balancing step takes place to correct for lighting differences and other radiometric issues in the images. If you haven’t already processed with a 3D Maps template, I would recommend you to try to process your project using this template.

3

Thank you for the response. 

I understand how to deselect the “Use Annotations” in the advanced tab of step 2 so that they are no longer used. How would I go about modifying an annotation once it has been saved in the image properties window (and after steps 2/3 are ran again with the "Use Annotations tab selected)?

 

So if I understand correctly, the only way to remove a previously applied annotation is to run step 2 again? Is it possible to see the Annotation on the image after you apply the annotation and then run step 2/3 again? 

For example, on the attached image when I’m creating the Mask I can see which part of the image is masked. However after running step 2/3 if I navigate back to the image that has the annotation I can no longer see the pixels that I masked out. Is this normal? The only indication that the selected image has Annotation/Mask is the Pencil icon next to the file name in the selection window. 

 

Thanks in advance.

4

Dear Ramiro,

at the moment the Global Mask cannot be modified directly on the images in the Image Properties Window. There is a workaround for this which is the following. In the folder …\project_name\1_initial\project_data\segments you fill find some files:

  • camera_name_globalMask.png shows the image coordinates of the pixels that are masked for all the images. If more cameras are present, a global-mask-png file will be created for each camera.
  • image_name_pixels.png
    - image_name_tree.p4b

Please delete these files in order to be sure they are not considered as annotations. You will notice that in the Image properties window the small pencil icon disappears next to the image name.

The files named image_name_labels.png refers instead to the Carve and the Mask annotations.

For more information about the different types of annotations, have a look at How to annotate images in the rayCloud.

If you want to remove the annotations but you cannot see them in the Image properties window, you can delete the corresponding files from the previously mentioned folder but at this point, you will need to save the project and reprocess Step 2.

The only case in which you don’t need to reprocess Step 2 is when using Carves (What is carve?). In this case, after applying the annotations and saving the project, you can directly export the point cloud, as explained in How to export the point cloud.

I hope this is helpful,

Alice