Height setting query

Hi all - I’d like to clear up a query I have regarding the height setting of a survey.

To illustrate what I mean I have a scenario. The area I need to scan is a beach and a vertical cliff into fields beyond. So in other words the land physically goes from 0m sea level up to about 50m (164ft) in a very short distance.

When setting up the scan I’m sure you’re aware that the height of the scan determines the density of the passes which the drone makes – the higher up it scans then the lower the number of passes it makes and therefore the lower the number of photos.

My question is; Does the software take into account the large step in heights on the map? Or if not which way round would you do it?
In other words if I was stood on the beach I would set the flight plan to be about 75m (246ft) in order to clear the cliff and allow a reasonable headroom above the cliff. However if I was stood at the top of the cliff then I’d probably set the scan to be about 15m (50ft).
The difference in the image density would be different when covering the same area.

Hi Dave, the software currently doesn’t offer terrain awareness. It’s been brought up quite a bit but hasn’t been implemented due to the number of potential issues it could cause. I would launch from the point where you feel you’ll get the best overall coverage.

Probably from the top of the cliff would give the safest option and the best quality / denser coverage.

What is the minimum height which DD needs?

Also, are the anti-collision sensors active when DroneDeploy is doing its thing?

The height thing makes a MASSIVE difference. For example; if I was to stand at sea level with coverage at only 70% side & front overlap and set the altitude to 250ft then the mission takes 19 minutes. However if I go to the top of the cliff and set the height to minimum (66ft) then the mission would take 220 minutes!!!

This is definitely something to consider for large changes in terrain height because it doesn’t take the terrain into account.

Dave, you could also try flying two separate missions and then combining the photos before uploading. Fly the top half of the incline in one, then plan a mission for the bottom half. Just make sure there is a little bit of overlap between the two missions. I’ve never done this, so I’m not sure how it would come out, but might be worth a try! You may have problems with elevation data, but if all you need is 2d ortho, it may work.

I thought about this. I thought I would overlap a lower altitude capture into a much higher “overview” area. Would it be possible to mix photos together from different heights into the same model??

I’m not sure, but even if you have to leave it as two separate flights, that may still work for you depending on what your goals are.

I would focus on flying at a higher altitude. Have you seen this yet? http://support.dronedeploy.com/docs/making-successful-maps