Colour Sandstone scaling error

Discussion in 'Technologies and Hardware' started by chad19, Jun 17, 2014.

  1. chad19
    chad19 New Member
    I tried printing in colour sandstone for my first time and ran into an odd error that I'm not sure is because there is an error in uploading or if it is because of the program I used to colour the model.

    I had printed a flat disk with a logo on it, 3.65" Dia x 0.2" Thick. When I received the print it was 2.78" Dia. x 0.2" Thick. It's my fault for not checking the dimensions on Shapeways before ordering but I can't figure out where the error is occurring.

    I imported the .stl into Photoshop and coloured it there, when exporting, it tells me the dimensions will be 3.65" Dia x 0.2" Thick, but when I upload it to Shapeways it turns into 2.78" Dia. x 0.2" Thick. It only seems to be affecting the xy dimensions as the z dimension always turns out correctly. I was able to trick the program by scaling up the diameter to 4.79" which uploaded to 3.65" Dia. so I can get the piece made correctly.

    I'm wondering if anyone else has run into this issue uploading from other programs or if this might be an error Photoshop creates?
     

    Attached Files:

  2. mkroeker
    mkroeker Well-Known Member
    Probably a photoshop error - the dimensions of your object as measured in meshlab appear to be consistent with (the metric equivalent of) 2.78"x0.2" ,
    but I have no clear idea of what might cause the curious scale factor of 0.76 (or 1.31) between expected and actual diameter. (Inadvertent application of current view zoom factor ? Something silly as "classical" 4:3 screen width:heigth ratio ?)
     
  3. chad19
    chad19 New Member
    Thanks for having a look at my file, guess I shouldn't trust Photoshop so much and just learn another program to do my UV mapping with.
     
  4. jhagen
    jhagen New Member
    I am having the same issue with Photoshop scaling for Shapeways. I am extruding 16 bit greyscale tif files, which are digital terrain models, in Photoshop, then adding satellite imagery as a color texture, then scaling it and exporting it using the Shapeways Full Color Sandstone settings. The preview shows the model at the scale I want, say 210mm. But then when I upload to shapeways and look at the dimensions, they are always smaller. Oddly, the files are usually about 10mm smaller whether the original was 50mm or 200mm. I wasted a few prints before figuring out that I had not made a mistake in my scaling. Something is happening in the translation from Photoshop to Shapeways. For now I'm doing the same thing Chad19 is doing, just scaling the file larger in Photoshop to accommodate the shrinking.

    Other models from other software retain exact dimensions, but I really like the Photoshop/Shapeways link. I hope this can be sorted out.

    Anyone have any solutions?