I had to fly across a swampy area with some tall-looking trees (like 100 footers) to take some photos of an old, old cemetery. To complicate things, the trees were standing on a 30 foot hill. Trying to make sure I could get as low as possible without hanging up in a tree, I flew to 250' AGL with the camera level so I could see the tops of the trees, and then tilted the camera down. The cemetery was 800' away (yes I did have VLOS), but judging tree heights versus the bird's height was scary. So, I wonder if any of you have used a laser range finder to check tree heights? There are Nikons for $150, and then a little math with Mr. Pythagoris can give me an answer. (Note- deciduous trees without leafs at this point!)
Rangefinder to determine tree height?
- Thread starter dxdy
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Barometric altimeters are notoriously inaccurate. The best method is still the camera view at slow speed. I would simply climb higher to get past them.
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That’s one of the very first things I did at my local park. The softball field lights are the tallest things in the park and immediate area, so I flew over, close, leveled the camera forward, and slowly climbed to determine the height. They’re all 60’ tall. So, my comfortable minimum at the park is 75’. Any higher I can fly everywhere (at the park) and not be to worried....set RTH at 75 too (again, for the park).
PatR
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Reminds me of a situation where a military agency had a problem where their “heavy iron” drones were ending up in tree tops during a certain phase of flight. Their launch and recovery area was dimensionally limited and surrounded by tall trees. To determine how tall the trees were they eventually used a small hand launched UAV and flew low over the trees and used the altitude displayed in the system controls.
CraigCam
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Judging distance between you and a potential object is very difficult. The problem of forced perspective is your eye and brain tells you that the drone is closer than it actually is. When you look at the screen, the camera view then is further confusing because it seems you are way far away from the same object. It took me lots of close practice with lower objects to understand how close I really am to an object and reconcile these two opposing visual clues. If an object ends up in your video frame on the bottom, you are close but safely over. It’s the left and right side that will crash you more as we are wider than we are deep and you can’t tell that through the camera.
I can tell you the more you try to avoid an object, the more likely you are to encounter it so nothing beats going over up high for safe passage. Wires are notorious for snagging drones and gimbals (been there and done that where brand new Hero3 ended up perfectly hung up on a power line by its new gimbal as the Chroma popped off its grommets and continued ascending) and tree branches are even more unpredictable because you can’t see all the little branches sticking out and up. I’m glad my objects are weird and low desert plants and cactus that the sensors can detect.
I can tell you the more you try to avoid an object, the more likely you are to encounter it so nothing beats going over up high for safe passage. Wires are notorious for snagging drones and gimbals (been there and done that where brand new Hero3 ended up perfectly hung up on a power line by its new gimbal as the Chroma popped off its grommets and continued ascending) and tree branches are even more unpredictable because you can’t see all the little branches sticking out and up. I’m glad my objects are weird and low desert plants and cactus that the sensors can detect.
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