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Scaling Help

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  • Scaling Help

    Hi Looking for some help if possible.

    I've done some smaller jobs where scaling hasn't been an issue. However I'd done a test on an exhaust manifold. The mesh results are great, not really bothered about the texture.

    So I've manually measured the manifold bore and stud sizes with my calipers. Studs are 5/16" and central bore is 35.75mm

    I then best fit a cylinder on the central bore and take the size and scale up accordingly.

    Now the bore measures 35.85mm. Good enough.

    The studs are slightly smaller but not too bad, however the distance between the studs is like 10mm off.

    I'm trying to figure out why.

    Is it because there is a gap between them and that is throwing it off?
    Could it be the type of images I've taken. (I took 100 photos and the software used them all fine)

    I'm running some tests on various objects to see what works well with scaling.

    I have a load of magnetic targets which I best fit a circle to and take the size and scale as I need to, so I decided to test using actual features on parts.

    Any help, advice, pointers would be great.


  • #2

    There are a few reasons why you might be having scaling issues, my initial thoughts are that if you're picking control points straight of the 3D surface, this can be considerably less accurate than setting control points directly on imagery.

    Depending on the version of 3DF Zephyr you are using (Full or LITE) there are a couple of different ways to set your scale. Using the full version of 3DF Zephyr you can utilize control points based on your images, set a defined scale distance and double-check on other parts to see how uniform your accuracy is: Control Points in 3DF Zephyr.

    Accuracy will vary depending on a number of factors, we have a calculator which can help demystify this a bit: Accuracy Calculator.

    If you're using 3DF Zephyr Free or LITE, there is a less accurate method for scaling which can still be applied and it's covered in this article: Scaling in 3DF Zephyr Free/LITE

    I hope this was somewhat informative - Let me know if you have any more specific questions about scaling in Zephyr!