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Author Topic: Checkered pattern in hillshade of DSM  (Read 388 times)

itzhalpepe

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Checkered pattern in hillshade of DSM
« on: May 06, 2021, 10:28:23 PM »
Hello together,
I produced a DSM with the Vexcel Ultracam X.

There I have a difference of 0,3 to 0,4 meters in the z-value, especially in steeper areas.

Therefore I generated a hillshade of the DSM, to prove, if there is an offset in x/y-direction, which would explain the problem in steep areas.

The hillshade shows a checkered pattern, which you can see in the attachement.

Maybe somebody had already the same pattern and can explain the problem?

Thanks

/leon








Alexey Pasumansky

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Re: Checkered pattern in hillshade of DSM
« Reply #1 on: May 07, 2021, 01:38:05 PM »
Hello Leon,

Which source option has been used for the DEM generation?
Can you please also provide the screenshot of the adjusted values from the camera calibration dialog and also specify the size of the observed "tiles"?
Best regards,
Alexey Pasumansky,
Agisoft LLC

itzhalpepe

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Re: Checkered pattern in hillshade of DSM
« Reply #2 on: May 07, 2021, 01:49:22 PM »
Hello Alexey,
the source of the DSM is the dense cloud and the interpolation option is disabled.

The camera calibration is in the attachement. The model was optimized by 3 GCPs.  But the calibration without GCPs is very similiar.

I also tried to  generate the DSM with fixed calibration of the calibration report, but this doesn't work. The research area is in complexe terrain in a high-mountain area with snow.

The checkered pattern is especially in shadow areas, where I have low values for the NIR. There I have also an offset of 0,3 to 0,5 meters, especially in  steep terrain.
In flat or sunny regions, the offset is clearly lower.

The DSM has a resolution of 0,5 meter.

/Leon

« Last Edit: May 07, 2021, 02:17:51 PM by itzhalpepe »

Alexey Pasumansky

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Re: Checkered pattern in hillshade of DSM
« Reply #3 on: May 08, 2021, 07:27:08 PM »
Hello Leon,

Was the low resolution image included to the depth maps generation procedure?

Can this problem be reproduced based on the smaller subset of images in the project, if so, maybe you can share some images and the project with the alignment, so that we can reproduce it on our side?
Best regards,
Alexey Pasumansky,
Agisoft LLC

itzhalpepe

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Re: Checkered pattern in hillshade of DSM
« Reply #4 on: May 13, 2021, 02:35:45 PM »
Hello Alexey, no, the low resolution image is not included.


I think the reproduction should be possible without the use of GCPs.

Maybe you can write me a personal message.

/Leon