Can you use the Phantom 4 to
measure distances (e.g. length on roof top)?

Depends on the tolerance you are looking for?

We just want to measure the length and width of the roof. It don`t need to be 100% accurate (just approx).

BaWCzfda4Vsa Posted at 2016-9-7 17:28
We just want to measure the length and width of the roof. It don`t need to be 100% accurate (just ap ...

Yes, you get a starting point of the flight, ask someone to note down the current distance, move along the roof, stop at the end, note down the distance. .... easy ....

OK. So there are no tools in the app that can measure distance, but you have to use the flight length? Correct?

I just measured my roof using Google Earth on the desktop.  Surprised to find out it was accurate within an inch with their Line tool.  The aerial photo Google has is fairly recent (Within a month as I moved stuff in the yard.) so the resolution is a lot better too.  Doing it by drone would be a lot more work and much slower.  I just checked my patio (Since it is on the ground) and it measured 178.45 inches in GE and I got close to the same ~1 inch).  I doubt if the drone will give you that sort of resolution.

There is no feature in the GO app for measuring. There are mapping apps.

gmccurdy@att.ne Posted at 2016-9-8 01:02
I just measured my roof using Google Earth on the desktop.  Surprised to find out it was accurate wi ...

I totally agree, Google Earth is pretty accurate and quick and don't have to risk your aircraft hitting a tree.

Thanks. We are going to measure roofs inside big building complex, so we cannot use Google. Anyone know an app we can use to measure images from a drone?

You can do it with photogrammetry software.
Ago soft or pix4D is good.
You are going to need to scale it with pre measured control points or you can use known dimensions of objects or structures.But
I would not use the wide angle camera of a P4 or P3P...

Thanks cedthered

Dr AJ Posted at 2016-9-8 02:36
Yes, you get a starting point of the flight, ask someone to note down the current distance, move a ...

Not so easy.
The distance shown is distance from home.
Unless home is in-line with the points you are measuring, you won't even be close.

labroides@yahoo Posted at 2016-9-7 22:20
Not so easy.
The distance shown is distance from home.
Unless home is in-line with the points you  ...

very easy ...
distance from home to roof point A noted, then distance from point A to point B noted, the difference gives the answer ...
very easy ...
and yes, i have done it ... home must be in line ...
simple mathematics mate ...

https://www.freemaptools.com/measure-distance.htm

https://www.freemaptools.com/measure-distance.htm

BaWCzfda4Vsa Posted at 2016-9-7 10:02
Thanks. We are going to measure roofs inside big building complex, so we cannot use Google. Anyone know an app we can use to measure images from a drone?

I measure roofs with drone pics often.. i use roofr.com just upload a photo and trace the image.  You will need one measurement for scale.