Missing areas

Hi, I’ve flown the same 200 acre area twice now with the same results. The first time I let DD pick the speed and ended up with some blurry photos so I wrote that off as the reason for the large blank areas of my map. I drove and hiked back out there a second time (over an hour to get on location) and tried it again at 20mph and 50ft lower, on a brighter day with very similar results. Over 500 images and 35 minutes to fly with a P4P.

I thought maybe it was because much of the ares is covered with a tree canopy but with GPS mapping that shouldn’t happen and besides, how to you get full coverage over a field of basically identical corn rows?

The map is actually shaped like a big reversed “L” Here is the map, any help is appreciated.

http://www.dronedeploy.com/app2/data/5a5fef07a5131159f0063674;jwt_token=eyJhbGciOiJIUzUxMiIsInR5cCI6IkpXVCJ9.eyJ0eXBlIjoiUmVhZE9ubHlQbGFuIiwiaWQiOiI1YTVmZWYwN2E1MTMxMTU5ZjAwNjM2NzQiLCJleHAiOjI1MzQwMjMwMDc5OX0.U6GXvMJSRyVeETjt-N3Cq2G6CQcW_j3Y2ONrNP5r8kNBb8-vLPa5oe_g4yzcxbSp3Hxsr419Lm7G193t1UIqQQ

Hello @Samphotodd,

I went ahead and looked at your Dennis Folk Roy 3 maps. I do see there are holes in your maps. This can be attributed to a few things.

  1. Your stitching may be a bit off. I would recommend setting overlap to 80/80 and flying at an altitude of 400 feet. I would also fly a bit slower. Judging by the photos, your area seemed a bit dark. Your shutter speed was about 1/60 which will cause some blur in your photos.

  2. Mapping tall trees are always going to be a bit difficult due to the nature of the subject. On windy days, capturing an accurate data set will be difficult as the trees will be moving. I would recommend flying midday and also when there is no to little wind. More information on better map making can be found here in our support article "Best practices to fly and stitch crop imagery"

I can go ahead and reprocess your map using a different algorithm. Hopefully this will produce better results. You will be receiving an email once that is finished.

Thanks!

@Samphotodd,

For several months I flew missions with 80/80 overlaps but recently tried 90/80 and got better results with no holes. My missions are at 200’ above the highest trees, so 340’ above takeoff point in my case. I fly on days with low wind, under 5 mph, and, due to the 90% front overlap, the drone speed was 9 mph. It took 19 minutes to map a 17 acres site of mostly trees using 1 battery on a DJI Phantom 4 Pro and the mission generated just over 400 pictures. I seem to get better results on overcast days but this slows the shutter speed and could require flying even slower than 9 mph. Your site is about 12X bigger so these setting will present a challenge for your large site. Like Yusuf says, fly at the 400’ limit if you are not already and fly as slow and use as much front overlap as you can tolerate.

I review every photo from my missions and remove any that are noticeably blurry which typically are at turns due to the drone rotating too fast. My last mission generated 434 photos and I remove about 20 before uploading.

Regards,
Terry.

Thanks for the info. I was flying at 350 on the second try and with a speed of 20mph. I had tried higher but things were worse. I did pull out a few of the blurry images but they were mostly at the very beginning and end or as SolarBarn said, during a rotation.

As for the when, I was at midday with some wind but not more than 5mph. Around here (Seattle), the sun never really gets very high this time of year and it was in and out so that was a challenge. I was 66/75 on the overlaps so I could for sure bump that up. It took two batteries and 36 minutes to compete. It will be rare to fly one this large and the smaller ones I have done came out great so this was a new issue.

Thanks again, I’m learning. It is quite the curve but worth it.

The small overlaps are the main problem. The photogrammetry in DroneDeploy cannot create a good 3D model without multiple photos of all areas. I noticed that on my 80/80 missions when I went to upload the photos that some of their positions were displaced, resulting in less overlap and thus fewer overlapping photos for the associated areas. And my maps had some small holes. On the 90/80 mission, the coverage was much better with excellent overlap between photos and no holes. I am looking forward to flying missions with 90/85 overlap to see if I get additional improvement. I am in Portland so I suffer your same sun challenges. You might enjoy seeing some of the results from my best mission in “Automatic Tree Detection and Characterization in DroneDeploy” which I posted to the DD Forum on 10 Jan 2018.

It is amazing that you got any result with only 65/75 overlaps.

Regards,
Terry.

Thanks, that helps, I was using the add on app from DD that suggests overlap based on height of the tallest tree and the kind of terrain. I’m a total rook, having only made about 10 maps, 9 of which came out really well and this one really sucked.

I much appreciate your comments and help.

Hey, I just checked the map and it is suddenly WAY better, not perfect but at least there are no holes. I was getting help from DD support and they ran it through some different process and the results are remarkable. Thank you Yusuf and your partners at support. I think I can make this work. Now that I understand, I’m make another trip out there and increase the overlaps and try again.

You know I had looked at pix4d and propeller and I’m sure happy I went the DD way, the support and community have been excellent.

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We’re excited to see what you’re gonna map next @Samphotodd! :slight_smile: