Model Dimensions

Discussion in 'Bug Reporting' started by AmLachDesigns, Jan 12, 2013.

  1. AmLachDesigns
    AmLachDesigns Well-Known Member

    I was looking at my model Roude Leiw Detailed pendant circle frame and the displayed dimensions appear to be incorrect.

    The model is essentially a disc with a loop attached and yet the dimensions suggest that it is round. I suppose that if one were to rotate it, it would fit into a box of the dimensions described, and this might be useful info for printing purposes, but is not useful to customers, I believe.

    Now I think of it I recall @bathsheba saying something similar in another post, but I cannot find it, sorry.

    Thanks in advance
  2. stannum
    stannum Well-Known Member
    Yes, it has been reported many times. Production bounding box is shown instead of uploaded file one.
  3. NimlothCQ
    NimlothCQ Shapeways Employee Product Team
    Stannum is correct; what you are seeing are numbers based on a re-oriented production calculation (OBB - Oriented Bounding Box) rather than the expected model bounding box and measurements (AABB - Axis Aligned Bounding Box). We understand that this issue is causing confusion and are working on a solution to display the right numbers to the right people, along with better communication on how things are calculated during the upload process.
  4. AmLachDesigns
    AmLachDesigns Well-Known Member

    I am in the situation of being careful what I wish for - the dimensions are now shown as I would expect on the public model page, which is good, but I think something else has possibly changed.

    I have a model heron inc base thicker legs hollow which is shown as cm: 10.454 w x 6.662 d x 14.898 h i.e. should print in pwsf. These are also the dimensions in Blender. However, I cannot select pwsf because the model exceeds the 150 mm dimension, apparently. If I go into edit mode for the model, there I get the Oriented Bounds box which is Cm: 6.66 w x 6.556 d x 15.752 h.

    Fair enough, I suppose (if I'm feeling charitable), but it is very irritating that I will only be able to get the right dimensions by:

    1. Adjusting my model;
    2. Uploading;
    3. Waiting...
    4. Checking the model in Edit Mode;
    5. Repeating until correct or I lose interest and do something else.

    If this is not new, but just because of the shape of my model, I apologise.
  5. NimlothCQ
    NimlothCQ Shapeways Employee Product Team
    Hi all,

    I wanted to let you know that the model edit page now displays both the original bounds, and the calculated oriented bounds (used for printability), as shown on the picture attached.




    Attached Files:

    Last edited: Jan 24, 2013
  6. AmLachDesigns
    AmLachDesigns Well-Known Member
    Yes, if you read my post, I referred to that.

    I did not know if this is new or not - I thought so.

    My point was that this information does not relate directly to anything in Blender, so getting something to be the max size for a given bounding box in the materials spec is a tedious process of trial and error. I suppose I could use Netfabb, but since I do not know the algorithm for creating a printing BB this would still not be sufficient.
  7. stop4stuff
    stop4stuff Well-Known Member
    All good, but why does the text need to be so big... I'm pretty sure most people who use the site are capable of reading the text no matter the size - personally, I feel that large text size is the same as the books used for young school children and is not needed for the extra scrolling involved because the text is so big, and to be blunt is quite demeaning for average adults.

  8. mkroeker
    mkroeker Well-Known Member
    So an object that has an AABB within the limits of a given material/printer will be rejected when the shapeways software
    finds some oblique OBB , e.g. oriented along the longest diagonal of the AABB, of smaller volume that violates the limits ?
    Sounds more like a bug to me (missing constraints in the OBB minimizer). Has it always been that way ?? (Granted that it may only
    hurt in a few fringe cases where the AABB is barely within the limits and AABB and OBB volume are probably very similar, but it is
    certainly counter-intuitive and I do not think we get to see the OBB limits in netfabb et al.)

    (Then an alternative solution for that poor heron might be not to scale him down, but to add some silly sprue that sticks out
    from his belly to derail the OBB calculation. Additional cost - a few cents, additional benefit - find out who realizes that a bird
    is not supposed to have a bellybutton)
  9. AmLachDesigns
    AmLachDesigns Well-Known Member
    Good idea about the belly button! I was trying to find a pun, something about a heron not being a naval bird, but to my great egret I could not find anything to fit the bill... :)
  10. mkroeker
    mkroeker Well-Known Member
    Another idea - develop that hero(n)ic statue along the lines of the old "never give up" cartoon :)
  11. AmLachDesigns
    AmLachDesigns Well-Known Member
    Update: I got my heron done and printed in pwsf. Very pleased with the result. I originally intended it for ceramic, but misread the materials requirements. Ho hum...

    Back on the Bounding box topic, I have this model

    Original Bounds: Cm: 8.9 w x 0.5 d x 9.9 h

    Oriented Bounds (used for determining printability): Cm: 8.4 w x 0.5 d x 10.0 h

    The major surfaces are all horizontal or vertical depending on the orientation in the printer, but my latest print had stepping on it which I could not understand, and certainly could not get explained to me. However I have just realised that the extra width provided by the hanging loop gives scope for tilting the whole piece in the printer some tiny amount, and judging by the above measurements rotating it a bit.

    Clever maths/algorithm, I suppose, but is it really necessary in this case, especially when it leaves me open to the dreaded stepping? Once again, has it always been this way or did the changes come in at the same time as the above noted changes?

    So, back to your belly button idea, mkroeker - if you want surfaces of your model to be treated as true horizontals or verticals, it may be necessary to game this process by the judicious addition of ... extra bits.
    Last edited: Feb 8, 2013
  12. mkroeker
    mkroeker Well-Known Member
    You could try using a pwsf model to make a plaster mold for slipcasting (provided you
    find a place to do the firing of the greenware piece for you).

    I do not think that the change in displayed bounding boxes within the customer-facing system is directly
    related to any changes in batch processing software behind the scenes, but there is probably an incentive
    to using automated software for closest packing, and automagic tilting of one of the objects in the build by
    just a few degrees may have been missed by the operator who checked the computed solution for

    (EDIT: had not noticed the context switch from heron to heraldry - as it is about the red lion standard
    that is convered in at least two other threads already, no need to suggest contacting CS)
    Last edited: Feb 8, 2013
  13. AmLachDesigns
    AmLachDesigns Well-Known Member
    You are right I have already let CS know about my concerns...

    But in my defence I posted in this thread purely about the BB, in the Prints One Day ... thread to offer what I hoped was a constructive idea (ok I went off topic later) it was only in the Am I Being too Picky that I was really whingeing uncontrollably.

    I'll take the hint and turn down the volume.