Pixel Estimating fitment for parts

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cleantune
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Pixel Estimating fitment for parts

Post by cleantune »

Have a picture of a part, but no dimension measurements and would like a close estimate of its size?
Some sites give dimensions on their parts, which are excellent for making carboard/ foam models, but some measurements on parts are not given. In order to try to avoid buying things that do not physically fit, there is a pretty cool way of approximating size of car parts from pictures by using photoshop or even microsoft paint by counting pixels.

Basically if one knows the size of something in the picture, one can count the pixels of this in the picture and then set up a conversion that can be used to calculate other things. In this case, the bolt size for these brackets were given, but the distance between the bolt holes was not.

For Photoshop:
1. first go up to "view" and select "Rulers". This will bring up margin rulers, which one can alter to set the "0" at any point in the picture (I ended up skipping this step and just used my own margins in blue).

2.From here (in CS6 version) one can click on the rulers and drag "x" and "y" coordinate lines onto the picture (in blue below) to the margins of whatever you want to measure (in this case I was looking for the bolt hole diameters and the distance between them). In older versions one can draw these lines with the brush tool holding the "shift" key for a straight line; skinnier the line the better (1 pixel thick is best).

3.Then click and hold on the "eye-dropper" tool and select the ruler. Using this tool and the shift key (for straight lines and also to help snap the measured line to the blue margins) draw a line from one of the margins (in blue) to the other. At the top of the page the length will be displayed as either height or width, depending on if the line drawn was vertical or horizontal.

4. Then just set up a conversion and solve for unknown pixels. In the example below, the bolt holes were for an M12 bolt (so roughly 12mm in diameter). Using the measuring tool, the pixel diameter was found and then divided by the diameter. The unknown length was then divided by this answer to find the length in millimeters. Its not exact, but its pretty close and the higher quality the picture is the more exact the answer can be.

Image

Link to a vid (*just take all the spaces out, it wouldnt let me post a working link for some reason) :
https ://www.youtube. com/watch ? v = Stp E E f u k LMg



Just tried this for the first time today and wanted to share the info :mrgreen:

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Last edited by cleantune on Tue Apr 15, 2014 8:36 am, edited 2 times in total.
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car6on14
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Re: Pixel Estimating fitment for parts

Post by car6on14 »

nice post, vid isnt working but Im into Remote control aircraft and this method should work for some products I see on other sites without info, thanks!
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cleantune
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Re: Pixel Estimating fitment for parts

Post by cleantune »

Glad you like it! Yeah it pretty much works for anything as long as you know the size of something and if this "something" is on the same face/plane as the unknown; even if its not, as long as the depth of field isn't too great one should still be able to get a really good estimate. I fixed the link too...kind of, just need to take the spaces out between the letters after you copy the link.

Little update: I ordered these same brackets and sure enough....

Image

14mm distance between the two mounting holes! Found out too that the reason I was getting two different measurements for the mounting holes was because both of the mounting holes were not the same size. The one that the "aftermarket" bolts (bolts that come with the mounting bracket) go through is about 0.5 mm larger in diameter than the M12 (12mm diameter) mounting hole. Amazingly enough, the 0.5mm difference is actually around the same difference found using the pixel measuring method (29.75pixels vs 29.29 pixels).

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PeterLight
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Re: Pixel Estimating fitment for parts

Post by PeterLight »

Definitely learning a lot from this thread. Thanks for the tips, fellas!
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