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Project in dense city with high rise building

I have aerial mapping about 600ha area with various building height, we usually flight at 150m but since there are a lot of tall building after initial check flight we fly at 180m, safely get all those images, but the rooftop tall building really looks close and covers many areas below, and after we processed with usual method the tall building stitching are definitely a mess. how can we threat such solution to get the the tall building still processed as octorectified imagery, do we have to fly higher again twice as building height? or is there any solution/tips-trick to do that.

in my opinion the pix4dmapper android should be able to capture the 4K video while on waypoint mission, so that areas covered by tall building distortion are still captured and can be processed.

thanks in advance.

Hi Mohammad, 

This type of project can be tricky for a drone. Indeed, the large differences in flight height create large differences in Ground Sampling Distances (GSD) across the project, which is difficult to reconstruct. More here: https://support.pix4d.com/hc/en-us/articles/202558979

This would also need a compromise on the accuracy of the project outputs. 

Another way to approach that project, would be to model the tall buildings separately. Then, to merge these with a project that covers the other areas without tall buildings. For the normal areas we recommend a double grid flight plan as here: https://support.pix4d.com/hc/en-us/articles/202557459#label8 for the tall buildings this flight plan could help: https://support.pix4d.com/hc/en-us/articles/202557459#label11

The 4K video has a lower resolution than still images, which is why we do not recommend their use for modelling.

Regards,  

is pix4dcapture circular mission available for dji phantom 3 pro? it shouldn’t be a problem applied in your app since DJI GO already have POI right? if can’t then how we should capture the circular mission with dji phantom? should be in autonomous/pre-programmed mode, manual control would be very difficult.

also I forget, there’re often problems sometimes the camera did not record anything, in our observation it sometime happen when lost signal/connection. how is that?

Hi Mohammad,

The circular mission is now available with Pix4Dcapture for DJI drones.

With the Android app, the action to shoot a picture is based on a time lapse that relies on DJI firmware that transfers the orders from the app to the drone. It can happen that several images are missed. For some reasons, which happens time to time and randomly, the images were not captured as frequently as set by our app according the computed time interval.

In January we released a new version of the app where the issue was fixed. Did you perhaps have the chance to try it out?

Best regards,