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This is one thread which we have a backup for after the forum disaster. The question has been lost, though. It is useful anyway.
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Formats. Mesh vs parametric (Restored)
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Prashant Kande
- Posts: 54
- Joined: Tue Jun 18, 2024 6:12 am
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Prashant Kande
- Posts: 54
- Joined: Tue Jun 18, 2024 6:12 am
Re: Formats. Mesh vs parametric (Restored)
Quick info discussion of formats:
STL is the simplest format available. It is basically a set of joined triangles (mesh)
Many formats are mesh-based.
There are also parametric surfaces where surfaces are defined with equations, and formats which support it. The top of parametric formats is STEP
The main thing is how surface of an object is defined. DGK supports both mesh objects and a number of parametric formats. How an object is represented is defined on per object basis
Mesh surface is simple to save/load and it is very flexible meaning that any shape can be represented. Very significant drawback is that is often difficult to modify, and the surface can look ragged for small size data
Parametric surfaces on the other hand are easy to modify by changing parameters in the equations. The surface is very smooth on the screen
A programmable CAD engine like DGKC particularly good for parametric modelling because with a bit a programming you can define a higher-level objects like burrs and modify your business-specific parameters (like diameter or helix) instead of generic geometrical ones
What you can do with mesh – based objects:
- Construct completely new mesh in memory programmatically
- Move the object around as whole with possible rotations and attach to other objects (Metrics sample)
- Perform Boolean subtract, union, intersect, clip operations (Bool Op sample)
- Clip the object with planes or other objects (Clip sample)
- Scale possibly differently in different directions (Transform sample)
- Delete or add triangles (Morph sample)
- Modify individual vertices (shared corners of triangles) of the mesh. (Morph sample)
- Do offset of the whole surface in orthogonal direction (Mesh Ops sample)
- Cut off a piece of surface using free hand curve
- We also have integrated inside Mesh Lab functionality, which has lots of operations on meshes like smoothing. We can provide you interface when you need something from there
The most generic mesh manipulation demonstrated in the Morph sample, but like always with meshes you need to know where the resulting position of each modified vertex should be.
Generally, if you need only to draw or move around objects with possibly adding measurements or evaluate distances, meshes are OK. If you need to modify the surface easily and precisely it is better to find parametric objects or remodel or construct programmatically as parametric.
Generally, conversion of meshes to parametric objects is difficult. Often it is better to remodel them. Meshes mostly come from 3D scanners these days
Kind regards
STL is the simplest format available. It is basically a set of joined triangles (mesh)
Many formats are mesh-based.
There are also parametric surfaces where surfaces are defined with equations, and formats which support it. The top of parametric formats is STEP
The main thing is how surface of an object is defined. DGK supports both mesh objects and a number of parametric formats. How an object is represented is defined on per object basis
Mesh surface is simple to save/load and it is very flexible meaning that any shape can be represented. Very significant drawback is that is often difficult to modify, and the surface can look ragged for small size data
Parametric surfaces on the other hand are easy to modify by changing parameters in the equations. The surface is very smooth on the screen
A programmable CAD engine like DGKC particularly good for parametric modelling because with a bit a programming you can define a higher-level objects like burrs and modify your business-specific parameters (like diameter or helix) instead of generic geometrical ones
What you can do with mesh – based objects:
- Construct completely new mesh in memory programmatically
- Move the object around as whole with possible rotations and attach to other objects (Metrics sample)
- Perform Boolean subtract, union, intersect, clip operations (Bool Op sample)
- Clip the object with planes or other objects (Clip sample)
- Scale possibly differently in different directions (Transform sample)
- Delete or add triangles (Morph sample)
- Modify individual vertices (shared corners of triangles) of the mesh. (Morph sample)
- Do offset of the whole surface in orthogonal direction (Mesh Ops sample)
- Cut off a piece of surface using free hand curve
- We also have integrated inside Mesh Lab functionality, which has lots of operations on meshes like smoothing. We can provide you interface when you need something from there
The most generic mesh manipulation demonstrated in the Morph sample, but like always with meshes you need to know where the resulting position of each modified vertex should be.
Generally, if you need only to draw or move around objects with possibly adding measurements or evaluate distances, meshes are OK. If you need to modify the surface easily and precisely it is better to find parametric objects or remodel or construct programmatically as parametric.
Generally, conversion of meshes to parametric objects is difficult. Often it is better to remodel them. Meshes mostly come from 3D scanners these days
Kind regards