Moving to the field of Aerial survey and photography for generating high resolution orthophoto maps. I’m currently focusing on smaller projects where consumer range drones should be sufficient. So after brief introduction to drone flying, setting waypoints and ground control points (GCP), adjusting camera, I was ready for a test.
My gear
Typhoon H hexacopter with CGO3+ integrated camera
EOS Arrow 200 GNSS receiver
Area
Test area is about 175x200m with high vegation, some buildings and rugged terrain, so not the easiest example.
Before flying I setup 5 ground targets and survey their location with EOS Arrow 200 GNSS receiver.
Software
For generating orthophoto I decided to test 3DSurvey software and DroneDeploy webservice to compare results. That was only thing I compared here, I wasn’t looking at different approaches, pricing plans or other features they are offering.
3Dsurvey
It’s standalone application so you need to process photos on your own machine. In trial version you get complete application without limitations for 14 days. I’m using standard laptop (Core i3, 1.7GHz and 4GB memory) and still managed to get results in couple of hours.
User interface is very straightforward and with nice semi automated wizzards, so basically you manage things with couple of clicks, but it’s still very good idea to look at tutorials published on their site.
3Dsurvey team advices you to use ground control points instead of EXIF GPS data, so I did that.
Main advantage is that you are in control of whole process, so you can for example manually correct point cloud to remove parts that are not terrain (vegetation, buldings,…) and you can recalculate some smaller parts of orthophoto to select best available picture.
Result (pan and zoom map with mouse and scroller)
3Dsurvey Orthophoto map (2cm resolution)
DroneDeploy
In trial you are limited to maximum resolution 5cm per pixel and you can only use EXIF data for location of every image, without ground control points. It’s very simple, you just upload your photos and wait for email that orthophoto is ready. That’s it, but on the other hand you can’t adjust any parameters or some parts like you can with own software.
Result
Conclusion
I’m quite satisfied with this test, although that is far from perfect. There are couple of mistakes, which I need to correct on next flight. Most important is to fly higher and capture images with more overlap. I also need to adjust some camere settings like white balance and shutter speed.
As for comparing 3Dsurvey and DroneDeploy look for the examples. Position accuracy is much better when using ground control points and overall I prefer own software solution for complete control over the process instead of web service.
Nice 3D model generated from Point Cloud
in the 70s I worked directly with aerial photogrammetry and used equipment to restore photos and generate cartographic base and its reliefs, the photos were taken from large aircraft and still had bugs to be fixed and I imagine how it would be possible with a light airplane without the flight plan fixes to get a good result in the photos or aerial images to the necessary digital corrections without defects to finally compile the cartographic maps or bases. I wonder what kind of application or corrections program exist to be used on images taken on board drones. I liked this technique material on this subject as current.
Thanks for sharing, well, things are a lot simpler now with new technology available to anyone. With the article I tried to show two of these options for preparing orthophoto’s and there are also others. But basically one approach is web service where you just upload photos to cloud and you receive generated results, no interaction and no special equipment for processing images needed. Other is to obtain own license of software and process images on your hardware.