Does anybody know what the Face Displacement property is for? Possible values are presented in a drop-down box containing the range from 8 to -8, zero inclusive and defaulting to 1. Changing the value does not trigger a surface rebuild or have any noticeable effect.
I like knowing how everything works and what everything is for, and it bothers me that I can’t find a mention of this property anywhere in the documentation or online.
While we’re on the subject, I’m curious also about the “Apply materials” property, which can be set to “Yes” (default) or “No”, and also does not trigger a rebuild or have any noticeable effect.
I’d much appreciate if anyone can explain what these are for or point me to where they have been explained.
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+1 to that
After a short search online I found this publication about face displacements in CAD models. I was not immediately able to make any sense of it and didn’t want to spend that much time reading. Maybe someone else can get something out of it, or just happens to know the layman’s answer.
https://www.researchgate.net/publication/264672878_Evaluating_the_effect_of_tolerances_on_the_functional_requirements_of_assemblies
Page 193 at the end is where it specifically mentions face displacement
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The Face Displacement is to help stop bleed through of surface color into e.g. Shaded Polygons that you place on a surface.
For example if you have a TIN model that represents a highway or Airport Taxiway or Apron. On that surface you draw filled polygons that represent markings on the surface (Striping, Symbols etc.) and you want those to be clearly visible on the surface without any form of bleed through, then use a Face Displacement of the surface of e.g., -5 to put the surface fill graphically 5 notches behind the polygon with fill - this is most clear when the fills have 0% transparency.
It is a graphical improvement that has zero effect on the surface elevations or the polygon elevations. Before this was available you had to change the elevation of the polygon so that it sat just above the surface to make it clearly visible without bleed through. The same applies when you have two surfaces that have common areas that are identical - if you set one of the surfaces to have the face displacement behind the other (-5) or in front of the other (+5) you should get a better graphical result without bleed through of one to the other.
Video shows how this works
For the Apply Materials - I think you must be using Beta 2024 or something because that is not in 2023 Release version - at least I am not seeing it in my 2023 version. I can check the Beta to see ehat that is doing.
Alan
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OK - on the Apply Materials property question - I cannot say that I had ever noticed that property but it appears that it works as follows
- It only appears when you create a surface out of 3D lines and Points where the lines have the Surface Sharpness property set to Sharp and Texture Boundary and where you have applied Site Improvements to the surface using the Apply Surface Site Improvement command. Once you have applied a Material that property appears on the surface and in my test the property was set to No. I then Created a Subgrade Surface for the bottom of engineered materials and the property was still set to No.
This Property did not show up at all when I built a test Takeoff Surface for OG or Design so it only appears to apply to the surfaces where you manually apply Surface Site Improvements.
The setting when set to No has no effect - the surface still has Site Improvements / Materials and it works as it should.
If I change the property to Yes it is then locked at Yes and I cannot change it back to No. That also seemed to totally screw up the application of site improvements if I deleted all of the SIs and then added some back they did not change the color of the surface where they were applied and when I built a subgrade adjusted surface they were not applied to create a subgrade surface.
I had never noticed the setting till now and I have never had an issue applying materials and site improvements to surfaces - this seemed to generate problems that I have never seen before - so my recommendation is leave it alone and don’t mess with it at all - I could see a purpose for it if it worked OK - but since it seems to not be working I would not touch it.
I think it was probably meant to be a switch that allowed Materials to be applied to the surface or not. i.e. you create the surface, you add SIs to the surface it should change to Yes because evidently that is what you wanted to do by running the Apply Surface Site Improvements. Later you decide that you no longer want / need the SIs so you switch it to No and it disables the SIs applied to the surface. That would make sense to me to have that option as a property. However it doesn’t seem to work that way.
This would be one for Trimble.
Alan
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Thanks Alan, this is exactly the explanation I was searching for. I knew someone would have inside knowledge about it. I had some notion of what “face displacement” ought to mean in the general sense, but it wasn’t obvious what it actually meant in this context. The more I know about the features in the software, the more effective I can be using it.
Totally agree - you are getting off into the long grasses here though buddy - watch out there are snakes out there !
Alan
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I am on 2023.10 and am able to see the Apply materials drop down. It only shows on surfaces with any site improvements applied