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Estimating Altitude? - 1/23/2006 7:49:10 PM   
Sky High



Posts: 1511
Joined: 12/3/2005
From: Atlanta, GA, USA
Status: offline 		I need some help from some really experienced pilots. How high would you say I was in the image that looks the highest in the thread below? I found a good way to judge altitude without an altimeter is by standing in one end zone of a football field and hovering in the other. That's a known distance of 300 ft. which is a great ruler or yardstick! So, I get a good reference as to the size (scale) of my helo at that distance. Then, when directly overhead, I can judge my altitude by how big my helo is in the sky.

www.rcuniverse.com/forum/fb.asp?m=3812072

< Message edited by Sky High -- 1/25/2006 4:33:17 AM >

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Never mess with a pilot having more rotors than you!
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RE: Estimating Altitude? - 1/23/2006 8:03:49 PM   
kd7ost


 

Posts: 402
Joined: 10/12/2003
From: Nampa, ID,
Status: offline 		I can't tell. It depends on your camera and the FOV as well as the angle it was shot at too. What camera and what size sensor? Are you sure it wasn't zoomed in any? 250 to 300 feet for me is right after take off or starting out on my downwing leg. At any rate you were most likely under 500 feet. There are instruments out there you can put on your platform that remove the doubt and debate. Using a camera picture to judge distance is pretty scientific. You need to know the FOV, the angle an oblique is shot at and the measurements of the most distance points on the ground that are in your picture. Different camera's shooting at the same FOV will also be different. You need to make sure to test the camera with measured references for accurate data. Without those numbers it's a grab bag. Obliques always look higher than true verticals. That's the way the human eye/brain connection works. I wouldn't be too worried about it unless you get too low.

Dan

(in reply to Sky High)
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RE: Estimating Altitude? - 1/23/2006 8:09:28 PM   
Sky High



Posts: 1511
Joined: 12/3/2005
From: Atlanta, GA, USA
Status: offline 		Thanks for that technical info, but, what's the highest you think I was judging by the images or video, dammit?

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Up there, you don't have time to think, if you think, you're dead!
Never mess with a pilot having more rotors than you!

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RE: Estimating Altitude? - 1/23/2006 8:15:09 PM   
kd7ost


 

Posts: 402
Joined: 10/12/2003
From: Nampa, ID,
Status: offline 		Nice attitude brainiac.

I think you were flying off the surface of Mars. You must be high anyway.

Maybe you should try to educate yourself a little and come back when you can talk to adults like an adult.
I can still help you out and give you a direction to start. I was ignorant once too.

http://www.rsr.org/sighting_pole.html

Dan

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       Post #: 4

RE: Estimating Altitude? - 1/23/2006 8:23:48 PM   
Sky High



Posts: 1511
Joined: 12/3/2005
From: Atlanta, GA, USA
Status: offline 		LMAO!!! Hey, I resemble those remarks! How many adults do you know that fly R/C? None, we're all big kids. Now, what do you think that smiley face was for? That was a friendly dammit......DAMMIT! As I stated, I appreciated all of that info but I just need a pro, like yourself, to give me a good estimate of my highest altitude. Thanks for the link, that was mighty Dan of ya!

The Ignorant One

< Message edited by Sky High -- 1/23/2006 9:03:44 PM >

_____________________________

Up there, you don't have time to think, if you think, you're dead!
Never mess with a pilot having more rotors than you!

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       Post #: 5

RE: Estimating Altitude? - 1/23/2006 8:39:08 PM   
kd7ost


 

Posts: 402
Joined: 10/12/2003
From: Nampa, ID,
Status: offline 		Perhaps you didn't read all the words in my first post about the infomation needed to do that. (Frankly you're seeming a little obsessed about it for some reason) I don't know if you were zoomed in or out. Do you understand that? What was your lens set at? 28mm, 32mm, 46mm etc? It throws off the numbers and becomes something I have to pull out of my.... What was the angle you shot it at. Same thing. FOV is needed otherwise I can sit here and tell you with certaintly that I'm pretty sure all of that was between 0 ft agl and 600 ft agl. Anything more dialed in than that becomes pure speculation. What are the distances between reference points out there.

You might as well be asking me how much I think you weigh based on your post. I don't have the information needed. (Probably between 0 and 400 pounds) You'll have to settle for that. You have the best idea how high you were because you saw all the pieces.

What's your real question or reason for asking? You seem to be holding somthing back. You must be "Sky High"!

Dan

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RE: Estimating Altitude? - 1/23/2006 8:47:48 PM   
Sky High



Posts: 1511
Joined: 12/3/2005
From: Atlanta, GA, USA
Status: offline 		Well, I have been estimating since I've been flying and finally used the trick with the football field described above. I had a conversation with someone in another forum that seemed to think that I was not nearly as high as I thought so I explained to them that I have always estimated, like most do, since I don't have an altimeter until I discovered and used the stadium method with the scale of the helo to the known 300 ft distance. So, I wanted to hear other more experienced pilots' opinions to see how far off I was. I think at the highest point I was at least at 200 ft. I'm going to find out how tall the stadium lights are at our other baseball stadium because they are tall as hell and I have easily cleared them before.

< Message edited by Sky High -- 1/25/2006 4:32:15 AM >

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Up there, you don't have time to think, if you think, you're dead!
Never mess with a pilot having more rotors than you!

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RE: Estimating Altitude? - 1/23/2006 8:54:29 PM   
kd7ost


 

Posts: 402
Joined: 10/12/2003
From: Nampa, ID,
Status: offline 		Well it sounds like you have a plan in place. Sorry I can't help you tell the other guy he's wrong. I'm one of those guys that has seen enough and been surprized about being wrong (when I swore I was right) that I've learned no amount of, "Hey what do you think about this....." is going to hold up in a court of law. You throw night lighting etc into it and human perception can whack so far out that you really need to discount it if you're trying to prove something. You can get yourself some facts and then come back and tell that guy he was wrong. (But you can't tell me that ) Simply because I didn't commit to a speculation.

Good luck

Dan

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RE: Estimating Altitude? - 1/23/2006 8:57:24 PM   
Sky High



Posts: 1511
Joined: 12/3/2005
From: Atlanta, GA, USA
Status: offline 		I don't know that he's wrong but I also don't know that he's right either. He didn't say that he was using an altimeter when comparing his aerial image of his estimated 130 ft that was similar in FOV as mine.

< Message edited by Sky High -- 1/23/2006 9:01:51 PM >

_____________________________

Up there, you don't have time to think, if you think, you're dead!
Never mess with a pilot having more rotors than you!

(in reply to kd7ost)
       Post #: 9

RE: Estimating Altitude? - 1/23/2006 9:07:39 PM   
kd7ost


 

Posts: 402
Joined: 10/12/2003
From: Nampa, ID,
Status: offline 		You know, not to kick a dead horse but certain visual perception can go way out of whack at certain times. Let’s use a comfortable example. The Harvest Moon. It sits low on the horizon and looks like its moved half of its normal distance away. I mean it's huge and just hanging there. (Only when it's low on the horizon though) You see it at night with normal skyline around and the human thinks the moon is fricken huge. It's not. It's the same size as always. You perceive it as being bigger in reference to the skyline and things you're familiar with seeing. Your brain is doing comparison with what it sees and what you’re memories are and tricking the heck out of you. Next time you see a harvest moon, turn away and bend over. Look at the moon from between your legs. This will effectively make the normally familiar looking horizon, become un-familiar. The moon will instantly look normal sized to you.

This doesn’t directly explain what could be going on and I’m not trying to suggest you’re wrong. But at night, with many normal visual cues gone from site, things look differently. Coupled with anxiety and a heightened sense of nerves your brain can make you see things in a way that they really aren’t. No one is lying. They see what they see. But it could easily be a Harvest Moon.

Dan

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RE: Estimating Altitude? - 1/23/2006 9:30:15 PM   
Sky High



Posts: 1511
Joined: 12/3/2005
From: Atlanta, GA, USA
Status: offline 		I think I will just take a picure of that scene and invert it. Otherwise, I'll have some explaining to do if I try the physical method out in public. Interesting though.

< Message edited by Sky High -- 1/23/2006 9:31:17 PM >

_____________________________

Up there, you don't have time to think, if you think, you're dead!
Never mess with a pilot having more rotors than you!

(in reply to kd7ost)
       Post #: 11

RE: Estimating Altitude? - 1/23/2006 9:38:08 PM   
Sky High



Posts: 1511
Joined: 12/3/2005
From: Atlanta, GA, USA
Status: offline 		I have definitely experienced some depth perception problems while flying causing near misses with poles that have almost been fatal. I have flown towards a pole with the helo 90 degrees or parallel to me and thought I was going to pass on the opposite side of the pole, when in fact, I flew by on the side closest to me. That is a strange sensation because your mind expects the helo to briefly disappear behind the pole but instead it is visible the whole time and then it hits you that you probably just had a near miss only a feet or a few inches from that pole. This is also true with altitude when flying near poles or structures. I grazed the top of a light pole thinking that I was at least 10 ft above it from the angle that I was viewing it and the helo, very misleading. I had flown through the goal posts at the stadium many times before from a head on orientation with no issues but a while back I was at a profle and finally struck one of the uprights because I miscalculated the distance of the center of the uprights and vertical pole closest to me because of depth perception and well, you know what happened.

< Message edited by Sky High -- 1/24/2006 12:09:39 AM >

_____________________________

Up there, you don't have time to think, if you think, you're dead!
Never mess with a pilot having more rotors than you!

(in reply to Sky High)
       Post #: 12

RE: Estimating Altitude? - 1/23/2006 9:50:37 PM   
kd7ost


 

Posts: 402
Joined: 10/12/2003
From: Nampa, ID,
Status: offline 		Lets throw the exercise the other direction.

How high do you think I was when I took this picture?

Dan

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RE: Estimating Altitude? - 1/23/2006 9:53:50 PM   
A10FLYR



Posts: 1282
Joined: 12/6/2001
From: Littleton, CO,
Status: offline 		I'll bet you didn't clear 200'.... We almost always think we are higher than we really are. You would NEVER catch me flying a chopper above the light poles at nite! My depth perception really sucks.

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Dean,
A10FLYR

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RE: Estimating Altitude? - 1/23/2006 9:54:04 PM   
Sky High



Posts: 1511
Joined: 12/3/2005
From: Atlanta, GA, USA
Status: offline 		Dan, I'd say.......pretty damn high!! Well, without a reference like a car or building, I would say at least 2000 ft.

< Message edited by Sky High -- 1/24/2006 12:11:54 AM >

_____________________________

Up there, you don't have time to think, if you think, you're dead!
Never mess with a pilot having more rotors than you!

(in reply to kd7ost) <