advice for an aerial survey on an industrial area

PIX4Dmapper PIX4Dmapper Questions/Troubleshooting
1

Hello everyone, I need some advice. I should do a an aerial survey with drone on an industrial area where the buildings are 40 meters high, there is a chimney of 60 meters high, and the presence of high voltage cables at 40 meters, everything was close to a Mountain.
I had to produce an orthophoto and a point cloud including the real parts of the buildings in order to connect it to a point cloud made from the ground using a laser scanner.
I have planned a nadiral mission at 80 meters agl (due to the fumes from the chimney) with photographic overlap of 80 front and 70 side. A doubt arises:
Do you think I should plan the mission so that the roofs of the buildings are also flown over 80 meters from their surface and therefore 80m + 40m agl?
Furthermore, in order to reconstruct the vertical parts, I thought of creating a second mission with a grid flight with a 45 degree tilted chamber.
I state that due to the obstacles it is dangerous for me to fly at lower altitudes, but theoretically I should program a flight height so that the gsd is not calculated on the vertical axis of the drone but on the axis of the camera facing the vertical subject, therefore the flight level was not 80 m but about 50 meters agl?
Thank you for the advice you can give me
Good continuation
Mario

2

Hi Mario,
Yes, you can create a second mission with the camera at a 45 degree oblique angle. This will be just fine. If you decide to image the vertical faces of a building then I recommend making sure the GSD is no more than a factor of two smaller than the nadir images. You can read a bit more in the article below.

3

Thank’s Mike.If i have undestood in the right manner, in case of ,for example,45° camera tilt,but generally not nadir position, the altitude is not the direct altitude from ground to drone (nadir direction) but the distance from camera to the target… is right?
Mario

4

Yes, that is correct. Furthermore, when you do image with oblique be sure not to image any of the sky as it will most certainly cause your project to not process well.

5

Thank’s Mike,thank’s for the support!
Have a nice day!
Mario