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Reverse Engineering From Photographs

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FokkerDVII

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Can anyone here point me to books that would detail how to create 3 view drawings from photographs? Many aircraft 3 view drawings were created from only one or two photos. What techniques are used? What kind of accuracy is possible? Anyway to use CAD?

Example: Use the first 3 photos to create an accurate side view drawing and then use that to develop full 3D fuselage drawings. Later photos show known dimensions.

http://www.fokkerfiles.com/dv/FokkerDVChallenge1.jpg

http://www.fokkerfiles.com/dv/FokkerDVChallenge2.jpg

http://www.fokkerfiles.com/dv/FokkerDVChallenge3.jpg





















 

autoreply

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Fairly straightforward with photo's that are taken from the standard perspectives in most CAD programs. Simply import the photo, scale, rotate etc and snap sketch lines to the photo. Lots of work to do it well though.

For your pictures, you can selectively scale the photo's you have to compensate for the perspective and then directly draw the whole frame in say SW.
 

Hot Wings

Grumpy Cynic
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For your pictures, you can selectively scale the photo's you have to compensate for the perspective and then directly draw the whole frame in say SW.
I've not actually tired it yet but to scale from photos that are not perfect side/front/top views it might be workable to trace/scale over the photos and then project them onto a second plane in a 3D program like Solidworks. One might even be able to project onto a curved plane and them unwrap to take perspective into consideration.

Getting a few hands on measurements and/or some photos with a verifiable part for dimensions makes the scaling much easier!
 

FokkerDVII

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For your pictures, you can selectively scale the photo's you have to compensate for the perspective and then directly draw the whole frame in say SW.
Without knowing the height and length of the fuselage, there isn't a way to know how much to accurately scale (skew) the photo. In the side view photo, the vertical fuselage members at the front are much further apart than they appear. They technique used predates Photoshop and CAD several decades. The book(s) I'm looking for are probably 50 years old or older???
 

autoreply

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Without knowing the height and length of the fuselage, there isn't a way to know how much to accurately scale (skew) the photo. In the side view photo, the vertical fuselage members at the front are much further apart than they appear. They technique used predates Photoshop and CAD several decades. The book(s) I'm looking for are probably 50 years old or older???
If you know one hard dimension (wheel diameter comes to mind) you can scale everything from there with amazing accuracy (a few promille)
 

Tiger Tim

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I started a similar project (not a Fokker but a one-off that no longer exists) a couple years ago. I got busy with other things so had to set the project aside but if you want to do the whole process on paper instead of CAD I think I can help.

-Tim
 

DangerZone

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Without knowing the height and length of the fuselage, there isn't a way to know how much to accurately scale (skew) the photo. In the side view photo, the vertical fuselage members at the front are much further apart than they appear. They technique used predates Photoshop and CAD several decades. The book(s) I'm looking for are probably 50 years old or older???
Even if you have perfect photos there will be discrepancies due to perspective. For example, a perfect side view from 5m away will only be to scale straight at the center of the picture yet the tail and nose of the arcraft will be viewed at an angle and distorted. Apart from taking the photos with TriTop or a 3Dscanner to have exact measures you will always have to take these angles into count. You could make good approximations but only plans could show you how much you drifted away from real measures due to perspective variation.
 

FokkerDVII

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I started a similar project (not a Fokker but a one-off that no longer exists) a couple years ago. I got busy with other things so had to set the project aside but if you want to do the whole process on paper instead of CAD I think I can help.

-Tim
It was done for years and years before CAD. I still have a drafting table, paper and drafting tools. I would love to see what you have.
 

autoreply

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Did you contact the Aviodrome?

They have the complete Fokker archive, including likely loads of documentation about this design...

Contact me if you need a Dutch intermediary (don't think I can be of much help). Forum member Paul Stalenberg might have some good contact too.

Bezoeken Aviodrome Historisch Luchtvaart Archief
Het Aviodrome Historisch Luchtvaart Archief is, uitsluitend op afspraak, toegankelijk voor (wetenschappelijk) onderzoekers, publicisten, etc. Afhankelijk van het type aanvraag dient mogelijk de normale entreeprijs betaald te worden voor de Aviodrome.
Gemotiveerde aanvragen voor toegang tot het archief kunnen worden gericht aan collectiebeheer@aviodrome.nl. In principe is het archief op dinsdag en vrijdag bemand.
De unieke collectie luchtfoto’s is voor een groot deel te zien op www.aviodrome.info en kunnen via collectiebeheer@aviodrome.nl ook worden besteld.

Het ADC grenst aan het Schiphol 1928 gebouw en bevat het grootste luchtvaartarchief van Europa.
Complete documentation of every single Fokker model apparantly is still in the archive.


Even if you have perfect photos there will be discrepancies due to perspective. For example, a perfect side view from 5m away will only be to scale straight at the center of the picture yet the tail and nose of the arcraft will be viewed at an angle and distorted. Apart from taking the photos with TriTop or a 3Dscanner to have exact measures you will always have to take these angles into count. You could make good approximations but only plans could show you how much you drifted away from real measures due to perspective variation.
Not at all. All of that is pretty easy to compensate if you know the lens used, or can reason back the lens angle (certainly possible in the pics shown). A lot of work, but these pictures are sufficient to accurately recreate the airframe if you know one reference dimension.
 

FokkerDVII

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Did you contact the Aviodrome?

They have the complete Fokker archive, including likely loads of documentation about this design...
The first 3 photos above came from the Fokker Archive. Many years ago I was in contact with the director. Prior to the Fokker Archive being set up many original photos and most of the blueprints were stolen. $1000 reward if you can find copies of the original construction blueprints for the Fokker D.V.
 

FritzW

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We used photogrammetry software back in my cop days to reconstruct crash scenes etc... might be worth a google. If we could pick up an accurate X, Y and Z of a few points on a photo (the more the better) we could just about put everything else back together. It was definitely one of those "garbage in garbage out" kind if things though.
 

Riggerrob

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Back around 1945, several model airplane magazines (Air Trails, Model Airplane News, etc.) published articles about how to derive 3-view drawings from photographs. At the end of World War 2, Allied engineers finally got to measure obscure Axis airplanes and found that their (extrapolations from photographs) were within 10 percent of the real airplanes. Ten percent is close enough for a replica, because you are going to want to do a full structurally analysis and stability profile before cutting any metal. Reviewing Graham Baslee's processes will help you understand how he can build replicas of World War 1 airplanes, that are tame enough for modern pilots to fly. Many WW1 airplanes were so unstable, and so difficult to fly that they killed more of their own pilots than bad guys. Trust me, you do not want to build an exact replica of a WW1 airplane. "Stand-off scale" is the only replica you are likely to survive flying. They showed a comparatively simple process, that starts with determining disappearing points, then extrapolating all the other dimensions. You can also find the process explained in textbooks that tell artists how to drawing buildings in perspective. If you already know the tire diameter, you have a good reference for extrapolating (educated guesses) of the size of other components.
 

Highplains

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The technique you are looking for is called "Single View Reconstruction" or SVR for short. Having the right search term is half the battle with Google. It has both graphical and mathematical roots and there has been some software done to facilitate the processes.

An example of how to do it graphically was presented in an article in Model Aviation (November 2010 issue). The graphic technique involves establishing vanishing points and doing some basic drafting.

To be real accurate from a photo, you need to know something about the camera in order to determine certain key aspects of how the lenses distort the image. Since you have multiple views, you should come very close to an exact replica.
 

Sockmonkey

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In sketchup you can import an image as a planar surface. If the picture is at an angle you can rotate the image to the approximate angle the picture was taken at and project it onto a perfect sidevew plane like so.
 

TFF

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Not a direct answer, but because Fokker had certain bulkheads as "standard" throughout the designs and the D V is on the linage of the E I-IVs, some data should be able to be extrapolated from the other planes.
 
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