Depth perception problems and eye tests - RC Groups
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Aug 06, 2017, 08:43 AM
What could possibly go wrong?
Discussion

Depth perception problems and eye tests


Hi, I'm not sure this is really the best forum to post this but it's the best I can see on a quick check.

Recently I've started to suspect I have a slight vision problem at longer distances. I can focus no problem way past the boundaries allowed for flying at all the clubs I've visited, but need reading glasses for anything closer than about 50 to 75cm. I'm 46 y.o. My sister wears glasses to correct a problem where she basically sees the world in 2D and I'm starting to wonder if I have some of this issue myself. I'd never wondered about it at all and never noticed any problem, until I recently started soloing RC models.
The same issue has happened a few times now - first time, I was landing at the mown grass strip at a club near where I live. I thought I was right over the further part of the strip, at a height of about 2m. Until that is, suddenly the model hit the ground, about 30+ metres beyond where I thought I was, and at ground level, not 2m altitude after all. There was a similar incident the following week, but I still came down on the mown area, just further away than I thought, and sooner. Yesterday at my home club, I was lining up for an approach (on my first circuit, I should have flown a warm-up lap I guess), and there are pylons with orange hi-viz traffic cones showing the runway approach. I thought I was right above these, nicely lined up to put the model down right on track. Instead, it went WHACK into a tree, again about 30 to 50m beyond where I thought I was, and lower altitude (not above the trees after all). That was kinda fun getting it back, but I was lucky and there was no damage to the model. Every time this has happened in fact the model has come home without damage, that's sheer luck, but it won't hold if I keep having this problem. I'm not that familiar flying at this place yet, and simply gaining experience and "getting my eye in" will help, but might also mask a problem if there is one. I'd rather get it checked.

Someone suggested this is a known vision problem, if I need to wear corrective spec's I'll do it - I find I'm reaching that age where you can't just assume everything still works as advertised any more, it takes some active self-support. I was hoping someone out there knows about this issue and can tell me how I can test my own 3d and/or distant depth perception for myself, and secondly, here in Australia, can you recommend someone/somewhere to get it tested, preferably on Medicare (I have a health care card). I don't seem to have depth perception problems closer up, I don't bump into stuff or miss things with my hands, I can throw and catch well enough, so I don't think I have a serious issue, though if this is a new problem manifesting itself at a distance, my guess is it'll probably affect me more over time I live in Perth (and I'm not just saying that for sympathy)
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Aug 07, 2017, 09:13 PM
Registered User
Well testing is best way to see the problem. Do you have trouble catching things when thrown to you? Do you catch it 100% of time or less than half? I have depth perception problems (none to speak of lost that years ago), no issues with objects nearby navigating a house or space familiar is easy, but distance: hello challenges. Flying planes has been interesting at times, yes met a few trees, landed short or long because I misjudged approach distance on landing. Change airfield anything like that can bring on problems

The biggest thing with RC planes is reference points to work with and have your eyes (brain) learn them. Switching plane size can confuse that too going from micro to 6 foot wingspan can upset the referencing system. Even if you have good depth perception, you can make those same mistakes, but they increase with no 3d.
Does watching a 3d movie look somewhat like a live show or is it just a flat screen?
some online test are out there http://www.mediacollege.com/3d/depth...tion/test.html
Most of them are ok.

Maybe it is just misjudging distances, only a few gifted people have that. I am not one of those but I learned to overcome it and believe it or not night flying is easy for me.

Try some of these test online if not next time you go to the eye doctor he should test you for that. BTW after 40 your corneas start to lose flexibility and that is why reading glasses become a new friend
Aug 08, 2017, 12:45 AM
What could possibly go wrong?
I don't think I've got a problem with that close up, I can throw and catch OK but at my age, and without kids, how often do you really get to try? It's not often someone says, here, catch, but when they do I can't tell if it's lack of practice or lack of perception if I miss... that said, I think I usually catch. Must try it again some time. I rarely bump into things, but then most of us are usually somewhere familiar. The more I think about it the more I think I'd have to have a check-up to be sure. Thanks for that link, that's a great start and I'll try it out.

The landing issue did come up when I tried out some different fields, I knew at the time I'd have to develop some reference points. The hardest I found was the place with the mown strip, it's all very flat land and there are few visual cues, being a learner I was mostly staring straight at the model. I'm trying to teach myself to keep checking references. There was one place near the coast with dunes covered in scrub, you rarely have no ground in your field of vision, and there's some tall smoke stacks at a power plant in the background. I never had problems at that place. I said I was back at my home field but I hadn't flown there for almost a year until 2 weeks ago, and I'd learned landing elsewhere then started it here again then, so I can understand it'd take time - still, it was a shock to suddenly find I was in a tree way past where I thought I was.

Thanks for the help, I'll get onto that soon as possible.
Aug 10, 2017, 01:41 PM
Registered User
G'day Bernie

I don't think you got anything wrong with your eyes ....Not too long ago I started flying a DHC Beaver (eflite one ) ...anyway this plane is fitted with flaps and ailerons and it is my first plane that I used for flying with ailerons (teaching myself the art of aileron control ) as all my other planes are RES gliders or just RE high wing birds .
The Beaver has a very long landing approach if the flaps are not activated and I have very nearly wiped out on two landing strip markers ( I fly at a private air stip )...just because my focus was laser like on the plane and the touch-down ended up right in front of where I was standing .

Try to get your touch-down further away from where you are standing ...maybe 30-40 meters , so you see the landing strip and your plane all in one frame and then over time , bring this forward as your eyes and subconscious memory get tuned in with your surrounds .

Like you , I need glasses for reading and anything I do with my hands up close . When I got my new set of glasses last time at Specsavers ( from memory these are called progressive vision glasses ) , I did mention to the optometrist that I need excellent clear vision for long distance flying of my gliders . He recommended a special kind of coating of the lenses for long distance vision and this coating will also cut out glare . He was spot on with his recommendation and I now use these same glasses when I drive at night to Perth with lots of headlights heading in opposite direction .

Hope that helps
Aug 15, 2017, 08:08 AM
I miss President Reagan
KMK001's Avatar
To start with, missing the runway is something we all do from time to time. It takes practice.
I was once told by a doctor that depth perception is pretty much useless beyond a certain range. Seem to recall that range is around 150 feet. Beyond that he said it's all learned response. Don't know how correct he was with that but casual observation seems to confirm.

In addition, as objects get further away, their details fade as do their colors. And it goes from highly defined to shades of out of focus grays. This all plays with ones ability to "judge" how far out and where in relation to everything else an object is.

But it won't hurt to get tested. And if nothing is found then you know you simply need more practice.
Aug 15, 2017, 09:13 AM
What could possibly go wrong?
Thanks KMK, that all sounds good. It came as a shock just how badly I'd misjudged the model's position. Putting it in a tree meant I was a good 50m past where I thought, which was only, say, 150m from the flight line anyway, not that far but I misjudged it by a third. Now when I fly circuits I make sure there's a good visual gap above that tree. Until I really know that place I'm just going to have to be careful. It's tricky lining up to land with the model flying toward you at an acute angle, and being winter it's often gusty so it can weather-vane the model.

You're right, I could be worrying about a non-issue, and of course I need more experience at this field, but an eye test is probably worth doing anyway. Turns out I can get it with little out-of-pocket expense on public health. A change in technique as TeamWilly says might help too, I've been lining up well in advance, with a long approach and glide slope. But, I think I'm going to do just the opposite and start closer. Unlike most trainers this model has a good sink rate, so I don't have to cut the throttle way back in the downwind leg, I can cut it on final and it'll sink fast enough. That way I don't have to fly way out the back just to start dropping in time. If anything that's the hard part of learning to land most trainers, IMO, because you have to start the approach out where you can't really see what you're doing, and you can't really see the glideslope until it's well and truly underway.
Aug 15, 2017, 11:33 AM
I miss President Reagan
KMK001's Avatar
Quote:
Originally Posted by BernardW
Thanks KMK, that all sounds good. It came as a shock just how badly I'd misjudged the model's position. Putting it in a tree meant I was a good 50m past where I thought, which was only, say, 150m from the flight line anyway, not that far but I misjudged it by a third. Now when I fly circuits I make sure there's a good visual gap above that tree. Until I really know that place I'm just going to have to be careful. It's tricky lining up to land with the model flying toward you at an acute angle, and being winter it's often gusty so it can weather-vane the model.

You're right, I could be worrying about a non-issue, and of course I need more experience at this field, but an eye test is probably worth doing anyway. Turns out I can get it with little out-of-pocket expense on public health. A change in technique as TeamWilly says might help too, I've been lining up well in advance, with a long approach and glide slope. But, I think I'm going to do just the opposite and start closer. Unlike most trainers this model has a good sink rate, so I don't have to cut the throttle way back in the downwind leg, I can cut it on final and it'll sink fast enough. That way I don't have to fly way out the back just to start dropping in time. If anything that's the hard part of learning to land most trainers, IMO, because you have to start the approach out where you can't really see what you're doing, and you can't really see the glideslope until it's well and truly underway.
I have a 40 size advanced trainer I use as my knock around plane. Added flaps and put an OS 61 FSR in the nose. You know the drill. Anyway, our club at the time usually flew left to right down the runway. 360 days of the year we would go left to right and being the expert lander I am! I greased in everything from the left. Then we had a day where the wind made us go right to left. Take off was fine but, I forget which flight of the day it was, I eventually landed it in a tree top about 100 yards out. Problem was I KNEW I had cleared that tree and was on my side of it. And I had around 30 years of RC flying at that point.

Happens to us all and doesn't take much of a change to screw everything up.
Aug 16, 2017, 09:25 AM
Registered User
Don Stackhouse's Avatar
Bernard, a VERY common beginner problem is letting the model get too far away, to the point they can't see it well enough to fly well.

This is where a glider can be a much better trainer than a typical power model. A fairly light 2-meter glider is easy to see, and slow enough to give you time to think (the one thing a beginner needs more than anything else!), and is also more comfortable to keep in closer, where you can see it. And, if it's an electric glider (so you have the option to power up and go around for another landing approach), so much the better.
Aug 16, 2017, 09:54 AM
What could possibly go wrong?
Thansk Don, to be honest the problem hasn't been excess range so much as correctly judging that range. I don't fly that far out, and I believe my eyes are good enough to see and orient the model at well over twice the maximum range I'm using, but I take your point. Early on someone explained the importance of good visual orientation, so it'pretty clear which way up and around my trainer is going. No strange Escher tricks mid-air, please! It has an orange/white sunburst on top, dark purple underside, the fuselage is blue and the tail surfaces are white, so I don't get confused.

I'm not so sure now I've really got a vision problem now, I probably just need more practice. I've only had my solo wings a few weeks but I figure this is the time where I build up the most valuable learning experience, so I'm taking full advantage of it. The weather isn't great now, we're right in the wet and windy part of our winter, but I don't mind and I go on the best available days. I figure if I learn to handle it when it's too blowy for most people, I'll get more flying days (and have the place to myself more often, too ). I'll still get my eyes tested but I'm starting to realise, this just takes time to develop. My eyes haven't normally had to do this job, trying to work out the distance of an object about *that* size about *that* far away, and hopefully it'll come. Even if I did have some sort of vision problem, I expect just getting used to the relative picture size of the model over familiar trees and terrain will soon be enough for me... but that one tree is still the problem! Luckily it has dense, small and springy foliage so it caught the model last time without damage, but I can't count on that forever. Thanks for the input.
Aug 16, 2017, 09:29 PM
Missileer Extraordinaire
Mel Duval's Avatar
An attack of the chainsaw beetle sometimes happens to problem trees like that.....
Aug 19, 2017, 02:34 AM
Requires Further Research :)
About “Depth-Perception” at longer distances.

Binocular (two-eye) vision is great for things that we can hold in our hands, ok out to about three meters, poor at six meters, and not worth much at all at one fifty meters.

One of the big clues about distance are knowing its’ size and seeing how big it looks off in the distance.

Other major clues are its’ relation to foreground and background. When it passes in-front-of a tree we know it is closer, when it passes in-back-of a bush we know it is farther. When it just passes over the bush or the tree we do not really know for sure its’ position.

When a plane is flying in a clear blue sky it is harder to guess the range. If trying to land on a featureless flat field then it will be hard to guess its range until it goes below the horizon and starts going in-front-of some features.

Good Luck
JD

There are also discussions to be found about what colors are easier to see than others, with white or bright colors being better than dark colors or black.
Aug 19, 2017, 02:55 AM
What could possibly go wrong?
Mel, I love it, it's just that one tree, gee I hope there's no infestation like that, late one night when no one's around... I just remembered the Kite-eating tree that tormented Linus from Peanuts. Same species.

JD, thanks for that, actually the more I think about it the more I think that's right. At that distance, forget 3D perception, it's just experience. I suddenly realised the last time I was there than the cross wind from behind me was blowing me so far past the runway I was in danger of hitting the inside edge of the tree line, and that also meant I had figured out the size-to-distance relationship of that scene. I give that particular tree a large vertical berth as I fly the circuit, sometimes I probably don't need to but better safe than sorry. In time I'll have a better idea exactly where I am in relation to it. Speaking of those cross-winds, I thought I was misjudging my approaches as I always seemed to put it down just the far side of the runway, but soon as the wind dropped I was right on the money, and I worked out it is pushing me out wide.

So I feel better about my eyes, just a panic I guess. A vision test can't hurt, I've had to start using reading glasses in the last year or so (right when I was building my first RC model, funny that...). Thanks for the input, very valuable.
Sep 14, 2017, 09:09 AM
Registered User
AFAIK, the binocular aspect of depth-perception ... is useful for objects which are within a very few metres of the observer. I seem to mind that, beyond about 5 - 10 metres, or so, binocular vision becomes progressively less reliable.

Whatever, at longer ranges, there are various visual cues which we use to estimate the distance of an object. .. relative sizes, colour and texture.

Trees are notorious. Best advice is to keep clear sky between the model and the tree, but at some point you have to descend below the tree-line. If the trees are a problem, you might investigate the use of some aids which can steepen the glide-path of your model; flaps, spoilers, side-slipping, even reverse-pitch.


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