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Lee D
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We've been doing some route surveys in forested areas and are having a lot of problems with the photos registering. Any tips and tricks for improving these results? More overlap? Fly higher? Fly lower? Any suggestions are appreciated.

I should add that we do the majority of the processing in Pix4D.

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Said Lot
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I'd suggest you supplement with higher flights near your ceiling.  The greater distance between you and the tree tops, the easier time it's going to have matching the photos.

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leegreen
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Lee D,

You left out a lot of variables.

A few questions:What are your side and front overlap?

  1. What is your AGL?
  2. How many flight lines are on your route?
  3. Are you using Terrain awareness?
  4. Are these trees conifers?
  5. Are the trees deciduous, what season? Are the leaves on or off?
  6. Is your camera NADIR or oblique?
  7. Are you using mapping grade GPS w/ GCP's, how many?
  8. Are you using RTK or PPK?
  9. What drone, sensor, and camera?
  10. Are looking for just an ortho-mosaic, or trying to calc 3d and elevations?

Mapping a route with a drone, I find you need at least 4 flight lines. Mapping deciduous treed areas are best down in the winter with only a few inches of snow cover. Pix4d will map through the trees down the ground survey. Mapping through conifers is almost impossible. Creating just the ortho-mosaic at too low AGL, may create camera mis-matching, if you don't have PPK or RTK and a good sensor.

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Lee D
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The drone is a Microdrone MD4-1000 with a Sony ILCE-7R 32MP camera. The pilot is doing something else today and doesn't have the controller handy but he believes the parameters were 75% side and 80% forward overlap flown at 60m AGL. No RTK, PPK, or IMU, just trying to register using the EXIF data and then add in GCP. All of the flights have more than four lines, 4 of the six were flown perpendicular to the route and the other two covered larger areas than just the route itself. The trees (on this project area) appear to be mainly conifer and are foliated. No snow in South Louisiana lol.

This time of year you're always fighting weather conditions... lighting, wind, etc. I just want to ensure that we're collecting our data with parameters that give us the best chance for success. We had six flights totaling 1887 images and Pix4D threw out 281 of them, all in areas of heavy canopy.

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makerofmaps
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Get Lidar.  https://www.microdrones.com/en/content/microdrones-mdmapper-lidar-preview/  

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Lee D
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I have LiDAR. The client wants photogrammetry.

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StLSurveyor
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Oh...I would like to see how this pans out...I've had the same issues. 

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leegreen
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Summer aerial from Google

summer1

 

Winter aerial from Pix4d

winter1

 

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