Hello
I am new to this Pix4D. I am planning to have solar installation. However, the people who are supposed to survey the place are merely salespeople and waste my time.
I am wondering if someone could guide me. I plan to use my drone to survey the roof and then upload the video Pix4D.
Which software should I download for the mapping?
I appreciate any help anyone can provide.
Hi Delta333,
I can suggest you two different softwares: the first one serves as quasi-auto-pilot for the Drone, and the second one is for the Mapping itself.
First, you can check if the manufacturer App can make a Photogrammetric flight: for example, Phantom 4 RTK can be piloted with DJI Pilot, which includes Mapping (one Zig-zag flyght pattern) and Oblique (up to 5 crossed flyght paths). In case the manufacturer App doesn’t include similar patterns, you can check Pix4D Capture (PIX4Dcapture: Free drone flight planning mobile app), which is free of charge even when you are not interested to process the images with a Pix4D product.
Once the survey is done, you can process the images with Pix4D Mapper (PIX4Dmapper: Professional photogrammetry software for drone mapping) in order to have full control of the Parameters and Constraints; if you just want an automated processing, you can also consider Pix4D Cloud (PIX4Dcloud: Cloud based drone mapping software).
About the flyght, be careful with the following points:
Height: no one of the abovementionned Capture Apps includes the possibility to load a local Terrain Model, and they rely on the information available online (Google Earth or Mapbox models with a km x km precision, and no infos about the Surfaces that are not Terrain). So, you cannot set the Flyght path to follow a localized sloped surface: you will need to mantain a safe distance from the roof. There are other apps that allow you to fly following a slope, or to import a local Surface Model, but they cost and so I never tested them. You can also check this list, and verify if one of these Apps allows the Sloped Flying path: https://support.pix4d.com/hc/en-us/articles/360047701131-Which-image-acquisition-app-can-I-use-with-Pix4D’s-software
Lighting Conditions: if the area is really clear, I suggest you to fly near the sunset or sunrise, when you already have some light but no shadows; if the area has a varied color palette, you can choose to fly either during sunset, sunrise or at midday (not the watch midday, but the moment when the shadows are as close as possible to disappear). As jolly condition, you can fly during an fully overcast day, but be careful: only a bunch of UAV models can fly during a rain…
Input Format: Surely you can process a Video with Pix4D Mapper; however, it’s preferable to process a set of photos, because depending of the Capture App and the Smartphone OS, the drone can also stop an half-second each time it takes a shoot, and so you can obtain a better Coordinates Tag. Personally I tested the Video proccessing in a residential neighborhood, and I didn’t enjoyed the result: I had to work a lot in order to remove the sky pixels (automated process with Parrot Bebop, but manual one with all other UAVs), and still I had noise on the resulting point cloud; surely I could take the measure I was interested, but the processing step was simpler when I did a new flight, this time of photos.
I hope you will find more infos in previous posts of this Community, and more tips and tricks in Youtube 
Have a nice survey,
Giancarlo