View Full Version : Thoughts on photographic perspective distortion
03-06-2017, 01:27 PM
How many of you, as artists deal with PPD or Photographic Perspective Distortion? It sounds like a TV commercial for the newest drug, but I find it to be, sometimes, an exasperating element of our craft.
I believe it to be, the effect of the curvature of the camera lens and how it gets transformed internally to the film or array as it may be. The cell phone camera, when taking pictures of a drawing, often really shows this effect, with the drawing or painting appearing to be out of perspective.
The exasperating part, is when you're working with photographs (or slides as it may be) and trying to reproduce the perspective on your 2D drawing and it just can't be done (at least in my limited experience). Often, I have to redo the perspective to make it appear 'correct' and often, it does not match the photograph at all. It looks weird, out of touch and just not right.
I'm not a fan of tracing the image, because that's just too easy for me, I'd rather have my 'impression' than a traced image. The digital reconstruction is a bit too sterile for my tastes, because I think there's a real difference, between an 'Illustration' and 'Art'. I like rendering my own vision, but the perspective distortion is a perplexing matter.
03-06-2017, 05:11 PM
As far as I understand it, it isn't so much a matter of lens curvature as much as it is a function of zoom and focusing. I don't recall the exact setting, but apparently out of all the options there are only a few that actually properly catch perspective. Unless carefully done, cropping a photo will make the matter much worse. I believe it is exactly for these reasons that many here have gone to 3D modeling.
I believe that there would be additional issues caused by the fact that we have binocular vision, whereas a camera is normally monocular. It means we can actually see a little around an object where a camera cannot so our brain really creates a composite. If you ride a bicycle with street tires, the really thin ones, next time you ride look straight down on top of the tire. Our normal perspective drawing would say you shouldn't be able to see where the wheel and tire are at the road, but there isn't any such issue.
It is a fun problem, isn't it? I think this is where those who draw from life get a much better feel for their subjects. It is definitely worth the practice.
03-06-2017, 05:37 PM
PPD certainly is a problem for artists . Probably the best answer I found was Joe De Marco's APM system ( Artists Perspective Modeller ) which used Geometric projection based on Joe's maths formulae to create a 3D perspective plot . In short it plots points from the plan 3 views and places them on a 2D sheet to show where they would appear in a 3D view of your choice . It may sound like an artificial /mechanical way of going about things but Joe was a very talented artist who could create a beautiful drawing from a handful of carefully selected points on the a/c. If you restrict the number of points you use it is reasonably quick to use but you need to be a good artist to construct the full image from a few dots . The good thing was that ( accepting Joe's word that his system was accurate) you could confidently create the perspective you wanted without recourse to photos. If you were prepared to invest a little time and key in numerous reference points from the plans you can create a quite detailed skeleton on which to base your drawing . Other than using this type of system or correctly shooting your own models ( or 3D models in a computer) you are as you say faced with correcting a distorted photo . Not an easy thing but the basics of perspective do allow us to draw some conclusions about how/ where a photo is wrong .
03-07-2017, 08:22 AM
Thanks for the thoughts on this. S15's points about this help explain it, to my brain, just a little bit better. Neil, I'd like to go with the 3D modeling, but that's already a popular venue in the rail simulation world and many of those, look really 'sterile'. I understand using the points of reference in a limited way and being more 'artistic', but I have to render it by hand, even if it doesn't match the photo (and often, it won't). Maybe I'm 'old school' that way. See the image below, as an example.
03-07-2017, 11:34 AM
Thanks RegisR . Pl don't misunderstand me . I'm not into 3D simulations as art . I simply use the 3D output as a reference /guide for a conventional drawing and/ or painting on paper or canvas. Simulations / 3D images tend as you say , to be lifeless . Somehow you know they're not real. Very few 3D artists produce convincing art work IMHO. I'm not averse to tracing an outline onto canvas as a starter . The art for me comes in the light and shade that brings the subject to life . I appreciate some folks want to do everything by hand and eye and encourage anyone who does .
03-16-2017, 03:07 PM
Just to reinforce Neils point above AMP is not really about 3d modelling, rather it is a very basic guide for perspective.
This image shows both the original APM plot and the painting I created from it.
As you can see APM allows for you to create accurate line drawings, with the correct perspective, but without the need for a photograph as the start point.
and a more complex scene
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