Low Light Mapping in Northern Latitudes

I´m just starting to use maps made easy, but have run into a problem I hope to get some help with. Up here in the north, days are short and dark, and even though I set the phantom´s exposure to manual and a shutter speed short enough to get sharp images, when I´ve flown a mission and check the images, they are all blurry as Map PIlot has set camera to ISO 187, which renders way too slow shutter speeds to get sharp images, which renders stitching impossible. How do I solve this?

Adam 2015년 12월 09일 18:05

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We have been seeing this a lot as winter is setting in... The truth is there might not be enough light available to capture good imagery using DJI's small aperture camera.

You could try slowing the aircraft down which will limit the smearing effect. Also, you could knock the exposure compensation down a step or two. Auto exposure is important to be able to use in aerial mapping but it can start to cause issues when there isn't enough light. Make sure you are mapping as close to solar noon as possible to maximize the available light.

Another thing to try would be flying higher since that will mask the effects.

Tudor 2015년 12월 10일 02:44

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What if we had the option to increase the ISO in the "settings"??

mrlbristol 2015년 12월 10일 02:50 1 표

Increasing the ISO setting on anything but the highest quality sensors (not the cheap sensor in the DJI camera) will add too much graininess to the images to stitch properly. The autoexposure of the camera knows this and only increases the ISO as a last resort.

In film, ISO was an OK tool to use since it was chemistry based, but with a digital sensor applying excess gain to the analog signals that are read out from each pixel adds too much noise to be useful. This is especially apparent in low light situations where the noise added in the digitization process will represent a large portion of the final signal. Do some lens cap or flat field tests to see what we are talking about...

We are of the opinion that ISO settings should be removed from the user controls in all but the absolute best digital cameras. Even then, it shouldn't be called "ISO", it should be called "Gain". The ISO settings are only there to help older hard core photographers transition from film to digital. Calling is "ISO" is masking the electronics that are involved and are doing a disservice to the public.

The graininess that happens with higher ISO settings actually happens in film too and does more harm than good when it comes to photogrammetric processing.

Tudor 2015년 12월 10일 15:56 0 표