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  #1  
Old 09-14-2014, 01:25 AM
SteveDana SteveDana is offline
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Photofield Accurate Distances and More Advice Needed Please

Hello,

Please see post below...

Last edited by SteveDana; 09-14-2014 at 01:38 PM. Reason: duplicated my post sorry
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Old 09-14-2014, 01:27 AM
SteveDana SteveDana is offline
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Hello,

I need some advice. I created a great pano of our field using my iPhone and pano feature. I stitched it manually in fotoshop and you can't even find the seam.

Anyway, so that looks great. The pano itself is awesome... The "horizon "is accurate... dead-on in fact...

The problem I'm having is adjusting the "distances", meaning for example, using google satellite, I know the road and where our cars park behind the field is 60-65 feet away from where I stand to fly in real life.

Yet when I taxi a plane out in RealFlight to where it looks like it's on the road, it says aircraft distance to "Pilot", me, is over 100 feet.

Our field is also a polo field and it's roughly 450 feet wide,
yet I can never get near the other side when it states aircraft is 450 feet away.

It's difficult to practice accurately with such distance discrepancies present.

And the inaccuracies only snow ball increase from there...

For example, in real life I "follow" the far tree line for a final to landing...
No problem... Nice and easy 300 or so foot glide to landing.

In the sim, I try or think to do the same and it ALWAYS come up WAY short,
because the perceived "tree line" is almost triple-quadruple as far away as real life...

(example 60 feet becomes 100, 100 becomes 200, and the edge of my field becomes 2000 feet plus when it's only really 500 approx...)

Also, when I goose the throttle a bit and move say, what would normally be a few feet, it (the program) says I moved like 20 feet.

So how do you adjust the size of the "world" so to speak?

I figured if I could "shrink it 30 percent or more the perceived "distances" would be closer to "real".

Even with my horizon "perfect", which it is, I cannot taxi out to the other side of my field which is only 450 away in real life.
The aircraft just keeps getting smaller and smaller to around 2500 feet and never gets to the "outside wall"...no matter where the horizon is...

I've been checking, looking, and researching these variables for days now.

No offense, but I think so far, people have been making photofields, they look great, so they fly them... and never really address or notice the "accurate/not accurate" distances in real life...

I am/was a CAD guy by trade and understand a photofield is an "illusion" rather than a truer 3d representaion.

Any help for this OCD brain would be greatly appreciated.

Thanks
Steve

Steve(dot)Dana(at)ymail(dot)com
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Old 09-14-2014, 02:32 AM
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Maj. Numbskully Maj. Numbskully is offline
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STEVE I cant post alink with my phone but look in the "RF7 Designers Corner" under "Creating My First Photofield"
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Old 09-14-2014, 09:34 AM
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While I'm no expert in this area, sounds to me like you got an iPhone quality pano. If I were to take a guess, I'd say that while your pano LOOKS right, its actually stretched vertically. I'm not sure which app you used, but the ones I've seen have you spin the phone 360 degrees and done. Well, the camera can't see past a certain angle, and therefore the true top and bottom of the pano are cut off. When you make it for RF, in order for the sky and ground to be covered, the pano has to be stretched to do so.

Just a thought. I might be way off base as I've never done it.
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Old 09-14-2014, 01:18 PM
SteveDana SteveDana is offline
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Using iPhone to create a pano.

Abaser,
Thanks for the response.

I used the standard iPhone 5 pano photo feature, no app.

Maybe others can use this as another way to create what is essentially a
Equi-Rectangular Panoramic.

Okay, I need to explain better how the pano was done.

It was not a simple 360 degree, spin around and "done". It was done in multiple 180 degree "passes".

First two passes were at the level of the horizon. Putting the horizon dead center of the image. Looking toward the field left to right, and what's behind the field left to right. Nice and slow and level. (the iPhone has a arrow and a guide line to keep it level as you go.)

Then I did the same thing a few times at increasing angles pointed upwards for the sky and then pointed downwards, for the ground. (Always left to right, from the same start/stop points, just at different angles until I had most of sky to the ground.

Then loaded all the 180s into the computer.

Using fotoshop,
I then created a 10000 x 5000 pixel blank fotoshop image set at 300 dpi.

I made a temp horizonal line layer at dead center left to right. (at 2500 pixel)
Then I made three vertical lines to "cut" the image into three vertical sections.
(2500, 5000, and 7500 pixel)

So first things first was to get the two horizon shots joined and lined up at the far edges as to match. (The far edges join in RealFlight so they need to match up exactly)

Then I added the next layer up to finish the tops of the trees and lined those up.

Then the sky etc etc and the ground/ grass etc etc.

It was a finished patchwork of multiple 180 degree pano shots and some "fillers"
from a few of the other 180s.

Then I color corrected everything so it looks like one massive shot.

There is absolutely no stretching.

When all was good I shut off my guideline layers and flattened the image to a .jpg file and loaded it into RealFlight.

That's when I noticed the distances are "wrong".

I can't check other people's panos for distances as I don't fly on their fields.

Again, thanks for the imput.

Steve in FL

Last edited by SteveDana; 09-14-2014 at 01:30 PM. Reason: spelling
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  #6  
Old 09-14-2014, 01:20 PM
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Maj. Numbskully Maj. Numbskully is offline
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The iphones lens is what is considered a wide angle lens therefore the distance vs. Scale and perspective are off .....i call it the "objects in mirror are closer than they appear" syndrem...


An iphone works great at Disneyland but was not ever intended to accurately reproduce scale as required in RF....it needs to be shot at what is considered a "normal lens" that being one the has the same perspective as the human eye ..(not wide angle/ not telephoto)

On ALL 35mm film camera the "normal" would be about 50 mm (its really49 to 52mm but they used 50 because of image circle ..."more on that later))

Its not so with digi's on them " normal " can vary dependent on the size and type of the image chip and its lenses "image circle" so unlike film cameras where 35mm is always 35mm there is no "standard normal focal length" on digital cameras it varies digital camera to digital camera.sometimes by 10s of mm's !!..on most digital camera lenes that zoom from wide to telephoto as a rule of thumb normal is about the middle of the zoom range...But i stress as a rule of thumb ...

"Image circle" is the other variable in all of this ...why?.....high quality high end lenses have a bigger image circle than cheap lenses at the same exact focal length to utilize the "sweet spot" every lens has ...bigger circle=.better sweet spot making a lens with a big circle requiers any or all of the following: more elements ..more expensive specialized glass or more complicated /expensive lens grinding process.... therefore more cost.
But IMAGE CIRCLE also alters what the "normal focal length" and perspective /distance/scale would be at any given focal length(and even alter the nodal point)

iphones can be equipped with snap on zoom lenses(can even be used remotly off of the phone can we say awesomeness !) they run about $250 using one of those and experimenting is the only way it would ...MIGHT work

I posted an example of the effects on focal length VS. scale ..distance and perspective in the RF7 Designers corner in a thread called "Creating My First Photo-field" i recently posted in it ....it was at the top of the list 10 min. Ago check out the 2 pictures of the mission porch i posted there....sorry i cant link with this phone...wish i had an iphone ! Steve's explanation of what he did sounds spot on to make a good field... its the car right side mirror syndrome thats killing him
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  #7  
Old 09-14-2014, 04:53 PM
SteveDana SteveDana is offline
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Distances... Close, but yet so far...

Major is right.

I check the specs on my iPhone 5 s camera.

It has a 29.XXXmm or round up to 30mm equivalent to 35mm.

So I guess Apple was/is trying to fit "more" picture into the frame?

How does more appear closer? Or does it?

If I use Major's "Objects in mirror are closer than they appear" assumption then yeah,
"More" of an image in the mirror, or this case image frame, would look further, but be closer.

But in RealFlight, the objects appear closer, yet the program measures the distance to them as "further".

This gets very confusing fast.

Either way, since the program is converting the panoramic into the half sphere "back wall" of the 3D environment , there must be a way to "adjust" the size of the environment.

For example, the 3D "world" RealFlight creates could be, say,
X measured mile by X measured mile circle with a half sphere dome plopped on top of it. I don't know what X equals, it doesn't specify the size of their "world".

The photofield image covers/wraps the inside of the dome so to speak. You then "fly" inside this dome.

Make mine smaller and we're all peachy here hahaha

Anyway...

I'd like some of the guys who've made photofields to check their distances too.

Just google map the satellite image of your field and use the measure distance tool.

You'll get a pretty darn good idea of the size of your field and how far everything is in relation to one another.

There was a guy who made one of our same field several years ago and his "distances from here to there" are "wrong" too.

Steve in FL
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Old 09-14-2014, 05:36 PM
SteveDana SteveDana is offline
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iPhone Lens adaptor ???

Major,

Would something like this help me?

http://www.slrlounge.com/ladibird-50...meraaccessory/

Now understand every iPhone version, 2,3,4, and mine is a 5,
has a different lens to begin with.

However, this seems like a stand alone add-on/accessory.

Steve in FL
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Old 09-15-2014, 12:17 PM
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Your best bet is to put some standard reference in the photo field.

e.g. a vertical ruler, a known fence height, etc.

Then when the field photos are imported to Realflight, put up one of the event height markers at 100% size, which are graduated in the same scale as the Realflight airports.

Put that up against your reference within the photo and compare.

You may end up having to take a few shots to "dial in" the correct zoom levels you'll need on your photographs to get the scaling right.

Once you get that down, and your photo horizon in line with the airport horizon everything else will be correct... E.G. airplanes will seem to be the correct size on the ground as they roll off into the distance, etc.

Too many of the Pano makers have not checked into this resulting in improper scaling and unrealistic photofields.... a few though have really hit the nail on the head.
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Old 09-15-2014, 01:07 PM
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That sounds like an excellent doable solution... I dont think getting away wish out trial and error is not possible ....but the only draw back for Steve is that as far as i know iphones cant "zoom" with out the forementioned aftermarket accessory lens ..... the iphone is only 8mp correct ?....a full fledged digital camera is still hands down the best way to make a field .....i have never experimented.....but I'm wondering if reducing the pano to say 6000 x 3000 would change anything ...i tend to doubt it will but than again I'm not to familiar in how RF utilizes the PI . I' m just thinking out loud
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Old 09-16-2014, 12:18 PM
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Another problem is of course tripod height. ( using a tripod and pano head is mandatory ).

The "eye" height of the pilot view in Realflight is not what the editor is reporting.

It seems to be off by about a foot.

That has a rather dramatic effect on plane size scaling and parallax.
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Old 09-17-2014, 02:05 AM
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What if steve is 5 '1 or 6'10 ? .......being off a
Foot or so might alter perspective some
But not necessarily scale they are 2 different animals.....again look at the example photos i posted in the thread i referenced above they are both taken from About 2 ft of the ground ....wish I had access to my PC ...I believe I have some piccs taken at the same exact spot at my eye level I'm 5'9 and as i recall scale doesn't change that much at all just perspective ....his main problem as described here and in previous PMs point to focal length issues .. I would love to see his pano and would have asked him to post or email them to me put thats pointless since my primitive phone wont show them and my PC is boxed and ready for shipping half way across the country my flight is on the 29th so i hope to be up and running on the 29th ...but the 1st or 2nd is probably more realistic
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Old 09-17-2014, 02:42 AM
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Think of it this way.....
A 3ft square box sitting on the ground will have an overall difference in percieved shape when comparing views of it with your head /eyes 1.5 ft off the ground looking strait at it than it will when you climb a ladder with your head /eyes at 9ft ...but doing so has not changed the size of the box only its percived shape.....a one side square to a 3 sided square thats pespective ....

Scale is the boxes SIZE in relation to distence

Looking at it from 2 ft away or 20 ft away the box again has not changed size but sure looks like it did espaecialy in 2 dimentional viewing ....and in photography its focal legnth proportional to field of view that alters that .. nothing else ...

Compare the size difference in the complete archway at the end of the hallway in my 2 photos to see what i mean they were both taken at the same hieght but with vastly different focal leanths for each shot...thats SCALE not perspective
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Old 09-17-2014, 03:10 AM
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Any of the above is not say that you do not need to shot at about 6 ft ...you do.
Thats RF's default eye level and is what the program is looking for just that steves problem seems to be focal leagnth IMO as I recall in his first PM to me he indicated he did shot at eye level at or very near the required 6 ft...steve can you confirm this i erased my messages to make room,......

Also would like to appologize to the grammer police for all the typos ...
An old G3 qwerty cellphoney with small butttons big fingers and a R and T button that refusee to work unless you mash them all without the benifit of a spellcheck does not make for a pretty post .......sorry
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Old 09-17-2014, 11:25 AM
SteveDana SteveDana is offline
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Maj,
I'm about 5'8" and shot the pano just above my eye level for the horizontal pass,
and a little higher for the sky passes and of course lower for the ground.

Yes- the iPhone has an 8 megapixel iSight camera.

Also- it has a artificial "horizon" line and arrow as a guide when shooting a panoramic.
You just pan super slow and stay on the line.

I do have a pro Bogen tripod but have to figure out how to mount the iPhone to it.

But as I stated earlier, there was a gentleman who made a pano of our field several years ago using the "traditional" method of creating the pano. And even his distances are not accurate.
His inaccuracies are similar to mine.
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