Solid.ByLoft Kinematic envelope

Hi everyone.

I am trying to generate the rail kinematic envelope for the clearance clashing detection report and I am having some issues with the processing of the block reference. As you can see in the image I attach below, something weird is doing with the polycurves and with the coordinate systems. The shape is well orientated but I don’t know why it is place in XY plane.

Besides, in another drawing that I have run the script, the geometry has been modeled but it is distorted in the curves.

Please find attached the .dyn and drawing with alignment and block reference.

Thank you very much.
Drawing4.dwg (1.5 MB) Kinematic Envelope.dyn (70.7 KB)

Ok I could sort it out the inconvenience with the polycurves. It was because of the geometry scaling. Now I continue struggling with rail shape distorted. I have used the node called “Solid.ByLoft” with guidecurves but it distortes the shape again…

I reattach the .dyn and .dwg

Kinematic Envelope.dyn (80.0 KB) Drawing1.dwg (1.7 MB)

Thanks in advance,

Hi, I’ve worked with a graph for this same case which provided results and was using the same logic as yours : block reference geometry applied at coordinate system of stations and using the solid by loft. I cannot share it here since I didn’t created it.

I will suggest trying to make the section smaller (eg. do just a quarter of the alignement) and increasing the interval to apply the blocks at curves. Seems to me that the problem comes at the curves so it will be the equivalent of increasing frequency in a corridor. Maybe that could help ?

Hi @david_licona . Thank you for your response.

I´ve chosen a 2 meters interval station and the issue still persists. The software goes crazy in the curves but as you say, I´ve seen other scripts with this workflow and they work in a proper way. I attach an image with the model and 2 meters interval station calculation.

I could check other scripts but they use the node Curve.SweepAsSolid. This node is wrong because the curve is only one section and it doesn’t take into account coordinate systems with the cant.


Create as many lofts as the profile pairs (like Civil 3D does) then join the solids into one and send it to Civil 3D

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Hi @Paolo_Emilio_Serra1 . I guess you´re referring to generate a loft per each interval station that I have and loft those sections with the guide curves that my sections have between those two intervals. Is that correct?

Later on, I will have, eg, 100 intervals sections = 100 lofts = 100 solids and you say to join those 100 solids.


Hi @Paolo_Emilio_Serra1 .

It works with your method but I struggled a bit to generate the lofts between sections and I don’t know if I have created an efficient graph. This is something that I had to face many times and I always sort it out the same way. To create the loft, for instance, in the second interval, I must repeat the previous point and the following one. To generate that, I have this approach but as I say, I don’t know if there is another one which it works in a better way.

Otherwise, find attached the script if you prefer to look into it deeper.

Kinematic Envelope.dyn (106.4 KB) Drawing1.dwg (3.2 MB)

Now that I have this workflow defined, I can apply it with rails as well.

Thank you again,

Hi @jmc.bimmanager, I tried this.

I think that your solution is not more accurate. Let me please know if I am wrong.
You can make more efficient graphs with this tool TuneUp Extension: Explore your Node and Graph execution times - Dynamo BIM

Hi @Drbohlav .

I appreciate your feedback. Please, can you share with me your .dyn version in order to explore it? I made few changes in my graph and I´d like to compare both and run the TuneUp Extension that you posted. I did not know that extension, thank you so much!

Have you tried to watch the solid in the Civil 3D interface or export it to IFC format? The main issue I used to have was when I sent the geometry to Civil 3D and the geometry wasn´t smooth. I sort it out creating a solid between every cross sections I had.

Hi @jmc.bimmanager, everything I’ve made is visible on the picture above. The picture of 3D solid object is from Civil 3D 2021.2. Kinematic Envelope_01.dyn (106.5 KB)

Hi @Drbohlav .

With your script, when I export to IFC format the geometry is distorted. See the image y attach below:

Try this updated script, where is old version (1) and new version (2) for solid creation.

Be aware of last piece of solid is missing. You need to play with the script little bit more. IFC model from second version looks better and it is solution as Paolo has written already. Kinematic Envelope_02.dyn (138.4 KB)
Version 1:

Version 2: