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Arc / Circle / Curve Segmentation in Sketches

don_williams909don_williams909 Member Posts: 52 PRO
Is anything ever going to be done to improve resolution of arcs, in both sketches and models?  Yes, I know, zoom in and eventually a curved part will stop looking like it has a bunch of choppy looking edges.
But not in sketches.

The segmentation of arcs just cost my company a lot of money because the designer who designed a part for us in Onshape couldn't tell that two arcs from two parts were actually intersecting and not tangent or creating a clearance between the moving parts.  Now we have to have 125 parts remade. 

This poor screen resolution has got to stop, and we need a curve to look like a curve in a sketch.

If the online-based CAD software can't create the bandwidth to show true graphic representation, then I'm sure that many of us would conclude that it simply can't keep up with installed-based software.
 
This is too important to ignore any longer.
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Comments

  • john_mcclaryjohn_mcclary Member, Developers Posts: 1,999 PRO
    edited June 8
    You can set the tessellation quality for each individual part by going to the appearance tool



    If you are still having problems viewing a decent resolution than the problem is your computer. On a day-to-day basis I hardly ever see segmentation even on large drawings.

    Go to system check in the "?" Menu and take a screenshot so we can take a look and rule that out
  • don_williams909don_williams909 Member Posts: 52 PRO
    You can set the tessellation quality for each individual part by going to the appearance tool


    John,
    It's not the part I'm concerned with so much as the sketches. The tessellation of sketch arcs is the issue here.
  • john_mcclaryjohn_mcclary Member, Developers Posts: 1,999 PRO
    Really?

    That's odd, usually the sketches are much smoother than the model.

    Can you show an example? How much detail is in the sketch?
  • PauloPaulo Member Posts: 19 ✭✭
    I think sketch arcs ok. Model edges not so much. 
    The segmentation of arcs just cost my company a lot of money because the designer who designed a part for us in Onshape couldn't tell that two arcs from two parts were actually intersecting and not tangent or creating a clearance between the moving parts.  Now we have to have 125 parts remade.  
    Should the designer be making parts by eye? I would take 125 parts from his pay 😉
  • don_williams909don_williams909 Member Posts: 52 PRO
    This is typically what we see when we zoom in on arcs.  These are actually very small arcs, the top one being around .315" R.
    It's not readily apparent if these two arcs are tangent or interfering, except that I added the center lines which might indicate that they are interfering.


  • don_williams909don_williams909 Member Posts: 52 PRO
    Oh - and those center lines are actually touching the arcs, not passing through them.  This sort of resolution is discouraging, because one has to create a lot of sketch geometry to figure out how the other geometry is off. It's more work than what is necessary.

  • owen_sparksowen_sparks Member, Developers Posts: 2,339 PRO
    @ilya_baran did a great interference detection custom feature. It's be interesting so see if that would detect the issue with your problem parts.
    Production Engineer
    HWM-Water Ltd
  • NeilCookeNeilCooke Moderator, Onshape Employees Posts: 2,350
    @don_williams909 can you share an example?
    Neil Cooke, Director of Technical Marketing, Onshape Inc.
  • david_van_der_meerdavid_van_der_meer Member Posts: 10 ✭✭
    I have experienced this issue on a design that I did to test Onshape (a real world design normally done in Inventor). It uses large radius circles to construct the geometry, and the sketch was very difficult to use due to how coarse it was. 

    Have a look at the sketch called "Left" and zoom in at the top of the sketch. It was difficult to constrain my because where the sketch geometry should be, is not where Onshape displays it. 
    https://cad.onshape.com/documents/f117870c7911e20bd0f5ca85/w/92859ff0d8ddd004afac131e/e/d4a615d87b73c270fe9b853b

    I just changed the tessellation quality of the parts to very fine following the advice in this thread, which made the parts themselves look a lot better, but the main issue is really with how coarse the sketch geometry displays.
  • larry_haweslarry_hawes Member Posts: 400 PRO
    Just came across this same issue. My part is not critical for production but it was disturbing to see the sketch arc versus the final part arc and the gap between. Took me by surprise then came back to this thread to see if there was a solution. Hard to imagine creating production parts with this issue.

    https://cad.onshape.com/documents/5c81a571f71fc3a99e3618a5/w/529996ec624ec76bec7f3570/e/1b3805724794a95af24cd737


  • NeilCookeNeilCooke Moderator, Onshape Employees Posts: 2,350
    Can somebody please file a bug if you haven't done so already? Thanks.
    Neil Cooke, Director of Technical Marketing, Onshape Inc.
  • larry_haweslarry_hawes Member Posts: 400 PRO
    edited June 15
    NeilCooke said:
    Can somebody please file a bug if you haven't done so already? Thanks.
    This is probably something everyone knows (but me?)  but how does one file a bug report?

    Might have figured it out here?

    https://www.onshape.com/support
  • NeilCookeNeilCooke Moderator, Onshape Employees Posts: 2,350
    As a pro user, go to Help > Contact Support
    Neil Cooke, Director of Technical Marketing, Onshape Inc.
  • larry_haweslarry_hawes Member Posts: 400 PRO
    Heard back from support re: the sketch segmentation as shown above.

    "This is purely a graphics issue as the arcs are not tessellated with a high enough quality to match the part."

    Obviously this response is accurate but how is this even remotely possible in a program like Onshape? How would it even be possible to model an example like one posted above by david_van_der_meer with segmentation as it now exists? Has this issue never come up before? And not addressed yesterday? 
  • Cris_BowersCris_Bowers Member Posts: 281 PRO
    I had this issue with a project I was working on too. The orange part in the top picture is the sketch that I have highlighted in the feature tree. The bottom picture is what the sketch looks like when I edit it. I don't have the tessellation quality set to very fine on the parts so they don't look aligned, but they are, and they look mostly curved when it is turned up. You would never know looking at my sketch that I actually had an arc drawn, it looks like 3 lines. It's a very large radius of 223'-4".

  • larry_haweslarry_hawes Member Posts: 400 PRO
    Not an expert user by any means but this seems like such a strange anomaly in a program where accuracy is the prime directive, but maybe it's acceptable to most users? It's been "marked as an improvement request" so I guess there's no real urgency...
  • david_van_der_meerdavid_van_der_meer Member Posts: 10 ✭✭
    I have been able to use Onshape for some reasonably complex part geometry, and to top it off it looks fantastic on a high DPI display as well. I've not really found this to be an issue before, until I had to work with these large radius arcs and circles.

    The design I linked to in my earlier comment was my first attempt to model one of the most simple designs in our organisation, with the intention to take this example to the design group to discuss suitability of Onshape in the production environment. You need to come well prepared and show how well it can work, otherwise you will end up being told how much better SolidWorks/Inventor/AutoCAD is.
    Instead, despite the overall simplicity of the design, I realised I could not go to them with this and present Onshape as a usable solution to them, as I struggled to accurately constrain this geometry. 
    After changing the tessellation to fine, I've now found there are material clashes in the model I couldn't see earlier, caused by me not being able to apply the correct constraints in the sketch.

    I can understand this behaviour would be required for performance, but you would expect some kind of auto-refine (or even a manual "regen" in AutoCAD speak) as you move in closer to the area you are working on.
  • tim_hess427tim_hess427 Member Posts: 142 PRO
    Just want to add my experience to this discussion in case its helpful. I have seen this behavior as well. Most recently, I was "using" a curved edge in a new sketch the curve had really large segments visible when zoomed in, very similar to the other screenshots posted here. 

    The trouble for me was that after adding a tangent line to my curve, I wouldn't be able to tell which line was the "curve" and which was the tangent. It didn't prevent me from doing anything, but was definitely annoying. I had to highlight the constraints to show which of the elements were actually coincident. 
  • larry_haweslarry_hawes Member Posts: 400 PRO
    I have been able to use Onshape for some reasonably complex part geometry, and to top it off it looks fantastic on a high DPI display as well. I've not really found this to be an issue before, until I had to work with these large radius arcs and circles.

    The design I linked to in my earlier comment was my first attempt to model one of the most simple designs in our organisation, with the intention to take this example to the design group to discuss suitability of Onshape in the production environment. You need to come well prepared and show how well it can work, otherwise you will end up being told how much better SolidWorks/Inventor/AutoCAD is.
    Instead, despite the overall simplicity of the design, I realised I could not go to them with this and present Onshape as a usable solution to them, as I struggled to accurately constrain this geometry. 
    After changing the tessellation to fine, I've now found there are material clashes in the model I couldn't see earlier, caused by me not being able to apply the correct constraints in the sketch.

    I can understand this behaviour would be required for performance, but you would expect some kind of auto-refine (or even a manual "regen" in AutoCAD speak) as you move in closer to the area you are working on.
    Onshape being what Onshape is, a modern, fast, responsive cloud based CAD solution designed for the professional and enterprise users with constant updates, it seems like even one story like this would be reason enough to change this behavior yesterday. I might be missing something but still find it a bit surprising.
  • NeilCookeNeilCooke Moderator, Onshape Employees Posts: 2,350
    Make sure that each of you reports it and details the problems it is causing. If the effect of a bug/limitation can be escalated the quicker it will get fixed. 
    Neil Cooke, Director of Technical Marketing, Onshape Inc.
  • don_williams909don_williams909 Member Posts: 52 PRO
    NeilCooke said:
    Can somebody please file a bug if you haven't done so already? Thanks.

    Neil, how is this a "bug"?  It's just the tessellation of arcs in the sketch module, no?
  • NeilCookeNeilCooke Moderator, Onshape Employees Posts: 2,350
    @don_williams909 a bug is anything which is undesirable behaviour. You could class it as an improvement but that would have less priority.
    Neil Cooke, Director of Technical Marketing, Onshape Inc.
  • don_williams909don_williams909 Member Posts: 52 PRO
    edited June 21
    Heard back from support re: the sketch segmentation as shown above.

    "This is purely a graphics issue as the arcs are not tessellated with a high enough quality to match the part."

    Obviously this response is accurate but how is this even remotely possible in a program like Onshape? How would it even be possible to model an example like one posted above by david_van_der_meer with segmentation as it now exists? Has this issue never come up before? And not addressed yesterday? 
    Larry Hawes, I've been on them for the better part of a year over this... so no, it hasn't just come up.

    Which just proves that Onshape isn't probably willing to increase the tessellation of the sketch entities because it uses way too much graphics processing power to do it, and it would probably slow their system down radically.    Notice that they side-stepped the question with their answer? 
    They didn't say that they can or are willing to increase the tessellation quality, just that it's not "high enough quality to match the part."
    So the reality is, they deem it unimportant to their priorities i.e. - never going to happen.



  • don_williams909don_williams909 Member Posts: 52 PRO
    edited June 21
    NeilCooke said:
    @don_williams909 can you share an example?
    I can do better... I can share the bill from the company who made the parts for us that don't work...
    :'(

    And yes, it was far more than an annual subscription for Onshape....
  • larry_haweslarry_hawes Member Posts: 400 PRO
    So the reality is, they deem it unimportant to their priorities i.e. - never going to happen.



    I think this is the surprising part to me, but there are complexities that I'll probably never understand. Can't imagine having production and productions costs at stake with this behavior and as you suggest the graphics cost must be too high to address this immediately?
  • john_mcclaryjohn_mcclary Member, Developers Posts: 1,999 PRO
    I'm sorry but that's why we make drawings. I haven't been sold on the, "Just share the model and hope for the best" approach.

    The fact they messed up your parts just because of tessellation means they have no clue how computer graphics work. A drawing that has a leader that has a proper radius callout goes a long way. Especially when you get a non-cad user that is muddling his way through it, and doesn't understand how computer graphics work. That and drawings tend to have finer detail when printed than some shop guy's old hand-me-down PC.

    So in the end, it is the fault of your detailer (or lack there of). Sorry not sorry, you do half a job and you got half a part.
  • tim_hess427tim_hess427 Member Posts: 142 PRO
    I interpreted the earlier post as saying "because of the tessellation quality, the designer was unable to detect interference between two arcs and subsequently a faulty design was produced". This is much different than saying "we had the guy in the machine shop was pulling dimensions off of a model to make the parts".

    These are completely different scenarios and I completely agree that the first scenario is a legitimate concern (especially without native interference/collision detection).  I haven't run into issues with clearances, but I have had difficulty selecting the appropriate entities which is annoying at best.
  • john_mcclaryjohn_mcclary Member, Developers Posts: 1,999 PRO
    even so with the designer making a mistake. The first thing we learn in cad was "Never eyeball anything!" Then he showed us how to zoom and we saw why.

    If the clearance was that tight, there is no doubt there should have been a double/tripple check. We all F*&% up now and again. But own up to your mistakes.

    tessellation 'should' be a well known issue for any computer graphics professional. It is annoying, but that's about it. "It's a poor craftsman who blames his tools"
  • larry_haweslarry_hawes Member Posts: 400 PRO
    Why not a couple sketch tessellation settings? Fine when needed with a performance hit and coarse for quick sketching?
  • don_williams909don_williams909 Member Posts: 52 PRO
    I'm sorry but that's why we make drawings. I haven't been sold on the, "Just share the model and hope for the best" approach.

    The fact they messed up your parts just because of tessellation means they have no clue how computer graphics work. A drawing that has a leader that has a proper radius callout goes a long way. Especially when you get a non-cad user that is muddling his way through it, and doesn't understand how computer graphics work. That and drawings tend to have finer detail when printed than some shop guy's old hand-me-down PC.

    So in the end, it is the fault of your detailer (or lack there of). Sorry not sorry, you do half a job and you got half a part.
    No, the machinists did not mess up the part.  You are jumping to the wrong conclusions.

    The parts were made to print.  The prints were detailed properly. 

    The problem was that the lack of proper arc detail caused the Engineer to not realize that there was a very slight interference in the design.  This part rotates, and it was supposed to just clear the other part, but instead it hit it, and was unable to lock into place properly.  There was virtually no way to tell that from the poor tessellation in the sketch.  Even if he had tried to create some test geometry, again, the tessellation would prohibit that from working.  Yes, he probably could have found another way to detect the issue, but the reality is that poor tessellation was the major contributor to the design error.
    I've used other CAD software where sketches had none of these issues.  The case for having dedicated CAD workstations with proper graphics cards and installed CAD software becomes stronger than having a web-based software that simply can't provide the same level of graphics quality.  Onshape has many wonderful qualities about it, most notably, their customer support team, but there are some serious shortcomings as well.

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