Overlap Sweet Spot for 3D Survey Mapping

Is there a Sweet Spot for overlap?

When I started out over 5 years ago using a drone for 3D Survey Mapping, I was told by others to use 80% or more for front and side overlap. Not having any real data to support a different setting, I used what was recommended. I eventually started using 70% side and 70% front for the past few years for all of the drones that I use.

I wanted to know definitively how changing the front/side overlap would effect the accuracy so I did a test case at 40%, 50%, 60%, 70% and 80% at 200 AGL (The X7 sweet spot). An earlier post showed the AGL test case.

Hypothesis: To determine how the front and side overlap will effect the XYZ accuracy.

Testing site: A 5 acre rectangular parcel that contains brush, trees, buildings and paved streets.

Drone Platforms: Inspire 2 with X7 camera, 16mm lens

AGL: 200'

Overlap: Front & Side 40% to 80%

For more details on the drone flight parameters see book "Flight Parameters" at www.cc4w.net.

Processing software: Metashape Pro by Agisoft

For more details on using Metashape Pro for 3D mapping, see books "Metashape" and "3D Road Intersection" at www.cc4w.net.

Five (5) GCPs were placed in specific locations on the 5 acre test site. One near each corner and one in the middle. Multiple checkpoints were scattered around the site.

For more detailed information on the NA, review books "What's My Mission?" and "Time to Fly" at www.cc4w.net.

The test site was flown with the Inspire 2, X7 camera/16mm lens.

Side Overlap Results

Front overlap results

Recommendation

Based upon the above results, two settings are recommended for the X7 with 16mm lens.

For Ortho only: 50% side, 50% front.

For 3D Survey Mapping: 50% side, 70% front.

Conclusion

I was surprised by the results of this test case.

I did not expect the accuracy to be maintained as well as it did at any overlap less than 70%. In fact, I expected 70% to be marginal at best.

Lens distortion is one of the biggest items to overcome with drone cameras which I have demonstrated on many prior posts. Determining the right settings to overcome lens distortion has taken me quite sometime to find the right speed, AGL, and now front/side overlap.

Just how many images will be needed for a project site? The more images the greater the processing time. Can there be less images by using a different overlap setting and still maintain the ASPRS mapping standard classifications?

After many testing hours of flight and processing time, the answer is yes.

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There are two training videos available on "3D Mapping" located at https://vimeo.com/ondemand/smms/

www.cc4w.net

"I fly Drones for a living mapping the earth one (1) acre at a time and write DIY surveying math/mapping books/videos for fun!"

Check out the New video series on "Survey Mapping Made Simple".

https://vimeo.com/ondemand/smms/

Sponsored by Cooper Aerial

Leaders in Modern Mapping Methodologies.

Cooper Aerial

A Free online "Flight Parameter" web app for multiple drone platforms is now available:

Click here to open.

If you like the information provided above and would like to see more in future email posts, then consider purchasing some of my books and videos to help support the effort. As all of you know, computer hardware, software and drones costs money. I put 100% of my book/video sales back into the business to write more books, produce videos, buy drones to test and so forth.

Thank you all that have supported this effort. It is greatly appreciated.

www.cc4w.net

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