Questions & Answers - Drones for Community Mapping

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  1. Are your drone images also being uploaded to Wikimedia Commons, for use on Wikipedia? - Andy Mabbett, @pigsonthewing
    1. Not currently, but many are posted on OpenAerialMap under open licenses. -Eugene
    2. this the imagery in the slide:,16.93503259011358,17/square/13230132221/5d29ec177a18fd0005e2978e?resolution=high&_k=kgkfae
    3. Arenda imagery:,14.537061956768639,15/square/13230312200133113/5dad0e1c16c43b00058d0262?resolution=high&_k=kizu9i -maning
  2. How do you produce DTM, are you sing Pix4D and what are the quick procedure
    1. Yep! I used Pix4D to generate DTM. You can check this diary entry I did for the Lupang Arenda example:
  3. Is there open source software for processing drone images?  Pix4d is not open source.
    1. Yes, you can OpenDroneMap which is opensource. -maning <3
    2. do you have any exeperionce
      1. The OSM community in the Philippines have a bit of experience using OpenDroneMap and we are now experimenting with various settings to try and generate optimal orthophoto maps.
  4. Do you have the base map of Batad uploaded online somewhere?
    1. Yep, you can check here:,16.93503259011358,17/square/13230132221/5d29ec177a18fd0005e2978e?resolution=high&_k=kgkfae
  5. This is awesome work! What were the reactions of the local communities that you worked with? Were they generally cooperative? Did they like the output when you shared it with them?
    1. For Batad, they do not like drones in the area because it was noisy. But after the team explained it to the people, they were okay with it. We explained as much as we can why we need to get the data for research purposes and for their use as well.
    2. For Lupang Arenda, the drone mapping was actually a request of the local government and they are now using the results of mapping in OSM as part of their rendering of public services. great to hear, thanks!
    3. more info about this community collab:
      1. thanks! great to see that there’s a lot of discussion about this!
  6. Are there privacy concerns (in case individual human beings are visible on the images) - do you blur these images, or ask people for their consent?
    1. the 10cm resolution is not sharp enough to identify faces/people
      1. Yep I agree.
  7. Is there any manual work for removing buildings for DTM, or everything done by software.
    1. To enhance DTM data, WhiteBoxTools’ RemoveOffTerrainObjects module was recommended by a colleague.
    2. This is done automatically by software. Note that DTM is not super accurate because it requires the software recognizing trees and buildings and this is not very accurate. But the DSM is useful.
      1. So the DTM is calculated from parallax between images?
        1. Yes! Pix4D and OpenDroneMap uses computer vision techniques to determine the “3D” shapes of objects and uses that to calculate the DSM.
  8. Are there privacy concerns about objects visible on private ground (in backyards, e.g.) not visible from the street level?
    1. In the works that I’ve done, we have proper coordination with the government officials down to the local community leaders to explain what we’re collecting. As much as possible we communicate with the community what we’re doing and collecting. So far, I haven’t had this before. - Leigh
  9. Do you have any equipments to adjust positioning like RTK or something?
    1. The drone itself has GPS capabilities to get the XYZ values. If the project / area requires higher accuracy in horizontal / vertical location, GPS Survey or adding GPS markers will help.
    2. We only rely on the GPS/GNSS technology included inside the drones.
  10. Great work! How do you choose locations/projects? What will be your next project?
    1. Usually from friends from the geospatial community ask us to map out areas. I team up with other drone pilots, OpenStreetMap PH community or involve Philippines Flying Labs to do the mapping.  Currently, I don’t have a next project due to the Corona Virus pandemic. Hopefully by next year, I can map again.
  11. How much complex to geo-reference drones’ shots?
    1. All drone captured images have the location in its exif metadata.  All images can just be in a single directory and the software can take care of the stitching and georeferencing.  This is the same for proprietary and open source tools.
    2. There are a few approaches to improve quality like taking nadir/perpendicular + oblique.  But in most cases, nadir images with 60-80% overlap will generate good results. -maning
      1. Thanks for this sir!
  12. What’s the cost of such drones?
    1. Oh it’s such a huge range! It ranges from 1500 USD to 25,000 USD. hehe. - Leigh
  13. What is your message for girls all around the world who want to learn to fly a drone?
    1. Go fly and enjoy it! Don’t be afraid of the technicalities of it. :)
    2. Go fly, and enjoy it (answer from Leigh) If people give you reasons not to, don’t listen to them too hard (indiebio)
      1. Why not “listen to them if they provide a reasonable explanation, and then make an informed decision taking into account this information” Would this require a different answer for women vs men?
        1. (I’m a girl and I would think yes - indiebio)
        2. There is good reason to encourage different groups of people, but that’s a question for a diversity talk (Gregory).
  • You are an inspiration for women all over our communities and seeing you giving a talk about a highly technical topic gives us motivation.
  • Thank You for the talk, and your time working on this project - Natfoot
  • I need to do more of this. Done quite a bit of the photogrametery simalar to pix4D from the ground using a poleand a camera. GoPro cameras work well as they have a gps.  You can do it! happy to help you as well!
  • [There’s a problem with audio feedback - maybe encourage presenters to use earphones?]
    • yes, please