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Motion Envelope Improvement Ideas

Motion Envelope Improvement Ideas

I've been working with motion envelopes a lot over the last several years.  This is an incredibly useful tool and my organization creates and uses them frequently.  However, they're difficult to create, difficult to use, and difficult to update.  It's time PTC gave this tool an overhaul with the end-users in mind.


  1. Ribbon toolbar
    • Replace the pop-up dialogue box with a ribbon based menu.
    • Separate this from the Playback tool.
    • This is where I should be able to select mirror planes, body options, frame of reference options, output options, etc.
  2. More envelope output options
    • Option to export a separate mirror part instead of, or in addition to, the regular envelope part.
    • Option to add a mirrored envelope to the same body as the regular envelope or add it to a separate body.
    • An ability to select the mirror plane.
    • Option to export and assemble the envelope to the mechanism assembly it came from.
      • Option to update an existing envelope if it was associated to the mechanism model in this way.
    • Aligned output options between MDX's envelope tool and BMX's Motion Analysis tool.
      • BMX's Motion Analysis tool has the ability to create an envelope feature directly in the feature tree of the mechanism it was generated from.
      • MDX's envelope tool can't do this. It only exports to the startup folder.
      • Both tools should have the same output capabilities.
  3. Change the frame of reference
    • Add an ability to change what reference frame (coordinate system) the envelope uses.
    • Currently, the top level coordinate system, or the ground, of the assembly is used. There's no option to change it.
    • I want to be able to change the coordinate system/reference frame used and have the resulting envelope represent the motion of parts with respect to it, not the ground.
    • This is similar in concept to a "paper part" in the Trace Curve tool where the paper part serves as the frame of reference for the motion.
    • I know of at least two Pro/Workarounds© to do this, but they're labor intensive and I don't want to have to use them. I want Creo to do this for me.
    • See this post from 2010 (@PAULKORENKIEWIC)
  4. Add a smoothing function
    • All envelopes have jittery facets that shouldn't be there.
    • Even flat surfaces have raised and recessed facets.  And because of how Creo merges coincident surfaces into a single surface, this seems to be a cause of export failures.
    • An optional smoothing operation should be added to the envelope tool. The user should be able to turn this option on or off with the understanding that smoothing adds computation time.
    • Sharp edges should be preserved.
    • OR just make the envelope tool better at generating smoother, less jittery surfaces without an added function.
    • See my post here:
  5. Add an option to update existing motion envelopes
    • Currently, envelopes are stand-alone objects with no connection to the mechanism model they were generated from.
    • Methods for updating an existing envelope depends on its part type:
      • If an envelope was created as a "Part", then the only way to update it is to manually overwrite it with a new envelope which is time consuming and cumbersome.
      • If an envelope was created as a "Lightweight Part", then you have the same option of overwriting as with a "Part" type envelope, but also by copying and pasting the "facet" object. Still time consuming and cumbersome.
    • There should be a way to update existing motion envelopes via the motion envelope creation dialogue box, regardless of the part type or other options selected (mirror solid, mirror body, mirror part, etc.)
      • This could be an option in the envelope tool which the user can choose in order to link the created envelope to the mechanism model it was generated from.
      • Envelopes which have been linked to their generating mechanism would then have the ability to be updated later.
  6. Add an ability to create compound motion envelopes directly
    • Currently, the motion envelope tool can only process one analysis file at a time.
    • If a compound envelope is needed, then the user must create one envelope, assemble it into the mechanism, and then create a second envelope using the first one. Time consuming and cumbersome.
    • You could generate a compound envelope with a single motion path, but this would not capture the entire possible range of motion and this becomes extremely cumbersome with more than two DOF's.
    • The envelope tool should have the ability to process two analyses at the same time in order to generate a compound motion envelope in one go.
      • Order of precedence matters when creating compound envelopes (which analysis is used 1st, 2nd, 3rd, etc.) so the user should have the ability to specify this or more ideally, Creo should automatically detect the correct sequence.
  7. Add debugging tools
    • When an envelope fails to export, what do I do? Where is the problem geometry? What are possible solutions? Currently, the user is on their own.
    • If I was able to export a part-type envelope without the solidification feature then that could be a way to get past an output error, do the export, open it in Creo, and attempt to repair it manually with the IDD.
    • The Invert Triangle Pairs tool is effective at resolving export problems, but it's difficult to tell where problem areas are.
      • When Fix Triangle Pairs is started, mesh statistics should be plotted on the previewed envelope and color coded.
      • Better yet, give an option to have Creo attempt to repair bad geometry.
      • Better yet, make this automatic when an export fails. Creo attempts to fix suspicious geometry and attempts to export again. If it fails again then it prompts the user.
      • But if Creo is able to identify and fix bad geometry, then why should there be an error in the first place?
    • Enable edge display for envelope previews. Currently, you can only see shaded with no edge display.
      • Putting this here since displaying edges during the preview could help the user ID problem areas.
      • The only immediately obvious way to see the envelope edges when troubleshooting a bad envelope is to export a lightweight part.
      • However, you can see the edges when you enter the Invert Triangle Pairs tool.
      • So it is possible to display them during the preview. So let the user control that with the regular edges/no edges display option.
    • Creo should detect if an exported envelope is going to fail upon solidification.
      • And it should tell the user where/why so the user can fix the problem with Fix Triangle Pairs if Creo can't itself.
  8. Add envelope statistics
    • The number of "triangles" is reported when an envelope is created and that's it.
    • What's their average size?
    • How long did it take to generate the envelope?
    • How many triangles have a good aspect ratio and how many are warped and how severely?
      • Plot the statistics on the previewed envelope as color coded values for aspect ratio, etc.
      • This could be a tool for debugging, help with spotting problem areas.
  9. The Motion Analysis tool (BMX)
    • Envelope creation by this BMX tool seems to take much longer than the MDX tool
      • Let's speed it up, please. The ability for this tool to put an envelope quilt in the feature tree of the mechanism it was generated from is too valuable for this slowdown to happen.
    • RegenRequest
      • When the analysis feature is changed from "Always" to "Read Only", the envelope quilt feature should be retained. Currently, it disappears.  If it was retained, then publish geometry can still reference it
      • Better yet, this tool should be able to export a standalone envelope quilt feature that exists independently of the analysis feature that it came from, but still be able to be updated by it.
    • Component Selection
      • Component selection for the envelope ignores assemblies and grouped parts.  In order to select the parts contained within them you must select them all individually.
      • MDX's envelope tool at least allows the selection of assemblies.
    • Update Interval
  10. Better documentation



1. Describe your environment: What is your industry? What is your role in your organization? Describe your stakeholders.

  • Industry:  wheeled machinery
  • Role:  product engineer
  • Stakeholders:  Every end-user who uses this tool and every designer who designs parts around other moving parts and depends on accurate and up-to-date motion envelopes

2. What version of Creo Parametric are you currently running?

  • Creo
  • Windchill

3. Describe the problem you are trying to solve. Please include detailed documentation such as screenshots, images or video.

  • Generally speaking, the problem we need to solve is the difficult and inefficient process of creating and updating motion envelopes.
  • Refer to the above text for all the detail you need.

4. What is the use case for your organization?

  • Every organization that creates motion envelopes would benefit from improvements to this tool, not just mine.

5. What business value would your suggestion represent for your organization?

  • Time saved inefficiently operating the program which can instead be spend on design work

1 Comment
Community Manager
Status changed to: Acknowledged

Thank you for your idea and the very detailed information provided.