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Micasense Altum processing

Hi all,

We are seeing a couple of problems consistently arise in our maps. One, the NDVI and NDRE layers don’t seem to be stitching properly. The maps almost appear to be patchy.

For the thermal, half of the maps are coming back fine, the other half are completely distorted.

Suggestions for these problems would be greatly appreciated!

Thanks

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Hello Sam,

We replied to the ticket in support. We need to investigate case by case why those artifacts appear as this can happen for multiple reasons. For example:

  • I have seen them when you collect data on partly cloudy days. The problem is that with scattered clouds, the illumination captured by the sunshine sensor is not representative of the illumination of the scene. It is difficult to correct for this.

  • The image png2pdf3: is usually caused by fast moving drones. Maybe you are flying too fast. Flying slower can help.

There is this nice article with some best practices I find useful Best practices: Collecting Data with MicaSense Sensors – MicaSense Knowledge Base

  • What I always recommend users is to capture nadir images, have 80% side and frontal overlap, capture data in “Clear sunny days as well as light overcast days in which the ambient light is not changing. Avoid capturing data in partly cloudy days with rolling clouds.” as MicaSense recommends, fly slow, fly higher

We will investigate together, and we can update it here as soon as we have results.

Best,

I don’t think this issue is because of clouds. It has happened repeatedly with completely sunny, overcast, and partially cloudy days. What we’ve also noticed is that there are a strange amount of negative NDVI/NDRE values on fields where we see this sort of pattern. Do you know why this might be?
Is there any information that I can provide you with that would help?

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Hi,

Yes please I need the datasets. I will write to you in a few minutes in our ticket

So we swapped out our sensor with the micasense team and the new sensor has fixed the thermal issues.

Unfortunately, we are continuing to see the exact same issues with the NDVI/NDRE layers. Now the weird part is that it is only on large fields (150+ acres), but we are seeing these issues on every single flight of that size. (patchy images and negative/low NDVI/NDRE values).

Do you know why this may be happening? It is certainly not a weather issue as we have gotten over 70 maps that look like this in different weather conditions and times of the day. Has anyone else experienced these issues, and how did you fix them?