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Measuring from Angled Photos

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  • Member since
    December, 2010
  • From: Portland, Oregon
  • 197 posts
Measuring from Angled Photos
Posted by Attuvian on Monday, May 08, 2017 2:48 PM

For scratchbuilds and kitbashing it's obviously best to have diagrams or line drawings with the major measurements noted.  But these may not be available for what one wants to work on.  So, we go to photos.  As long as a firm measurement can be found somewhere (i.e. wheelbase, height of drivers, etc.), one may be able to easily compute other measurements with some accuracy.  It's simple proportional arithmetic - IF WHAT YOU WANT TO MEASURE IS ON THE SAME PLANE AS YOUR REFERENCE ITEM.  And even then there are potential issues of parallax depending on the overall length of the unit and the type of lens through which it was shot. 

But chances are that your photo was taken at an angle as side shots of cars and engines are not generally taken on a perpendicular.  Let's say that the best photo you've got for a unique caboose is an angled view and you need to measure that strange widow at the far end.  Not much of an issue if you know how tall the side wall is and all you need is the window's height.  But it is if you want the LENGTH of that window or the car body extension in which it was installed.  That's where the "error of the angle" really comes into play.

Does anyone know of any photo programs that do the geometry for you and can artificially reproduce a view of the car wall at 90 degrees?  Then's it's just measure, recompute to the reference, and get to work with that styrene on your bench.

Surely this is not a new issue.  I've searched through the MR sites and forum listings but haven't come across anything yet.

Obliged,

John

  • Member since
    April, 2009
  • From: Sweden
  • 1,288 posts
Posted by Graffen on Monday, May 08, 2017 3:32 PM
I only know how to reverse draw it... That's how you make 3 view plans from perspective photos.

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  • Member since
    December, 2010
  • From: Portland, Oregon
  • 197 posts
Posted by Attuvian on Monday, May 08, 2017 5:30 PM

Thank you, there in Sweden!  I've just been reading more on this through Google.  I think what I'm dealing with here is creating an "orthographic projection" from an image in perspective.  I'm quickly finding that I'm "getting into the weeds", a quaint expression for which there must be a few Swedish equivalents.

Ha en bra dag.

  • Member since
    April, 2011
  • From: About 20 minutes from IRM
  • 290 posts
Posted by CGW121 on Monday, May 08, 2017 8:54 PM


Paint Shop Pro has a tool to straighten images that are at an angle, forgot what it is called, I would assume Photo Shop and gimp do as well.

 

 

  • Member since
    December, 2010
  • From: Portland, Oregon
  • 197 posts
Posted by Attuvian on Monday, May 08, 2017 10:44 PM

Thanks, CGW.  Now I may be getting somewhere. And, yes, it looks like both PhotoShop and GIMP have it as well.  And there are on-line tutorials.  Both Paint Shop and PhotoShop have 30 day free trials.  GIMP appears to be free straight up.

But for the rest of you guys reading this, don't hold back with your suggestions.  I ain't there just yet!

John

  • Member since
    February, 2017
  • From: Ayer, MA by way of Queens, NY
  • 30 posts
Posted by TheGamp on Tuesday, May 09, 2017 1:13 AM

I've been using SketchUp for my car build, and have made extensive use of its Match Photo feature. It's not automatic, but it lets you load one or more photos, overlay your rough drawing, then reposition the origin and pairs of perspective vanishing lines to line up with major contour lines in the image. Then you adjust the grid spacing to match a known measurement, and from that point tracing the edges puts you in the general ballpark. 

  • Member since
    December, 2010
  • From: Portland, Oregon
  • 197 posts
Posted by Attuvian on Tuesday, May 09, 2017 3:20 AM

Thanks, Gamp.  I'll check that one out, too.

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