Dealing with incorrect marker placement

[dowallin]

Greetings. I am using the Orthophoto/DEM with GCP tutorial. I've aligned my images and I am placing markers. After finding a marker in a single image, I filter photos by marker. I then go through the images one at a time to refine the marker location. I have run into two different situations where the marker location is incorrect.

1. I some cases the view of the marker is blocked by a tall tree but the marker position is more or less in the correct location in the image if the tree wasn't there or if you could see through the tree. So in this case, I right-click on the marker and select "Remove Marker."

2. The other case which is less common is when the marker is place on an image that definitely DOES NOT cover the position where the marker is located. On the Model tab, this image is clearly in a completely different part of the study area. In this case, I also right-click on the marker location and select "Remove Marker."

Am I doing the right thing in both cases?

Thanks for your help.

David

 

 

[SAV]

Hi dowallin,

In case 1 you DO NOT have to remove the markers. Just leave them as they are.

In case 2, you DO have to remove all incorrect markers.

If you are dealing with UAV imagery (i.e., geotagged images), you might want to follow this 'optimised' workflow I have outlined in a previous post:
http://www.agisoft.com/forum/index.php?topic=7851.msg37494#msg37494

It will help you to speed up processing :-)

Let me know if it works for you.

Regards,
SAV

[macsurveyr]

Hi David,

You are in fact doing the right thing in BOTH cases.

A marked marker is only correct if it is in fact marked only on the visible, unambiguous target. It is incorrect to leave a marker just because it is more or less in the right image location. The actual target must be visible.

Tom

[JMR]

Case A (or the tree hiding target) if blue flag=>delete marker, if gray flag just dont care. Be carefull in case you have automated image based marker refinement, it is a great feature but a bit prone to cause wrong guesses and mess things. Keep in mind that, if auto refinement is enabled, gray flags may turn to be blue after pinning the marker in some other photos requiring your attention.

Case B a marker in weird location way off of its place. Might be due to auto placement. Blue flags MUST be removed or draged to their right positions. But if the "mad" marker is gray then it is likely the photo is not propperly aligned .

Best,
GEOBIT

[alanjohnseymour@gmail.com]

Other than python script,
How can one change all blue (not totally correct, but used) flags to gray (non used) flags?