Flat map badly distorted

I tried making a flat map from a single line of images shot in a straight linear path. There's quite a bit of overlap. The results came out unusable. One ended up as a narrow strip. The other had images that seemed mirrored and badly distorted.

Used a Mavic 3T with Map Pilot installed into a DJI RC Pro Enterprise controller. This combination of hardware doesn't have a "Quickmap" option as the iOS version does.

I tried it twice without success. Any idea of what might have happened and how it can be prevented? Thanks.

https://www.mapsmadeeasy.com/maps/public/fc87185906de423a8763a13600d4c9d5

https://www.mapsmadeeasy.com/maps/public/a87bd873551b47d782271d04d3f93c96

Dean Sensui February 13, 2024 03:15

Official comment

Please read about Flat Maps and what they are intended to be used for here:

https://support.dronesmadeeasy.com/hc/en-us/articles/360054461812-Flat-Maps

This doesn't look like the kind of area you would want to use a Flat Map in.

As noted in the Data Collection guidelines that are agreed to at the time of upload:

Job Shape - When doing long, linear jobs, make sure to do AT LEAST three passes so there are enough perspectives to reconstruct the scene. Increased overlap will need to be used to make up for the lost width. When doing few passes don't do a straight line. Either put a kink in it or use more passes.

One straight single pass can end up getting rotated so we have this requirement in there.

Zane February 13, 2024 04:15

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3 comments

Thanks for the reply. I read the article earlier and that's why I was trying the Flat Map feature. It said "Works with single pass linear missions" and that's what this was trying to test.

This particular flat map was only a test to see how it worked because it's right in front of my house so it's not an assignment. However, I do need to know what's needed to make it work since we're going to be doing shoreline surveys which are essentially long, narrow maps that don't have a lot of detail.

In particular we want to do thermal maps with a Mavic 3T but so for we haven't had any success. So for now I'm seeing if I can at least do this with a visual map.

What I found puzzling is the distortion of one of the maps where it ended up being a narrow stripe. The article stated that flat maps were comprised of the original images positioned according to GPS data and didn't rely on photogrammetric clues.

And right now the RTK feature isn't working even though it was functioning last week.

Dean Sensui February 13, 2024 09:17 0 votes

The flat map is not the one that is mirrored. The flat map will have discontinuities between images where they are blended into the other images. The flat map is calculated based on the pointing angles that are recorded with the image. For the best results in a flat map you should fly much more slowly and use lower overlap. 15 to 20% is ideal.

The flat map insurance that you will actually get a result. If you do a single pass, you may not get anything usable which you have already found out.

Zane February 13, 2024 14:11 0 votes