On what bases AutoCad can measure dimensions of non Autodesk 3d objects?

[Anonymous]

I am trying to measure dimensions of non Autodesk 3d objects (which mostly are short cylinders of 1 or 2 micrometer length). 

On what bases AutoCAD can measure dimensions of these non-Autodesk 3d objects?

[TheCADnoob]

Are you trying to figure out how to use the DIM command in AutoCAD, or are you trying to figure out how to change the UNITS in AutoCAD or are you trying to figure out how AutoCAD get the unit data from the files?

Activate DIM if you want to perform a measurement

https://knowledge.autodesk.com/support/autocad-lt/learn-explore/caas/CloudHelp/cloudhelp/2016/ENU/Au...

Activate UNITS to change the units to Microns. This will also require a standard to scale by.

https://knowledge.autodesk.com/support/autocad-architecture/learn-explore/caas/CloudHelp/cloudhelp/2...

[leeminardi · Accepted solution]

Are you asking how can you measure the distance between two points in an AutoCAD model?  If so, you can use the dist command. You would probably want to have object snapping set to end and nearest.

Since you are using dxf files the objects are valid AutoCAD objects (Autodesk is the name of the company that sells AutoCAD). The file 24a.dxf is a tessellated model representing a 3d shape as a collection of triangular flat surfaces (known as faces). It could possibly be converted to a solid model which would enable volume and other mass properties to be determined. The file N24-N25 3D appears to be a collection of planar section cuts represented by short line segments.  What type of analysis would you like to perform on this model?

[Anonymous]

Hi lee.minardi

 Thanks a lot for the kind response. 

About the first part, I am trying to measure the dimensions of this 3d object (as short irregular cylinder shown in 24a.dxf). these measurements typically include Volume, surface area, length or height, and perimeters and cross-sectional areas of both ends of the cylinder. Is that possible? I used dist command to measure the length of this cylinder and found it typical to values I got from my 3D reconstruction software so I have no problem with length.

I attached a photo of 24a.dxf showing perimeters and cross-sectional areas I want to measure.

Secondly, as I mentioned I need to get Mass properties (essentially the ones written above) of the solid model of 24a.dxf. I attached other N24-N25.dxf just to show my original 3D object from which I cut (in my 3D reconstruction software) short cylinders at certain spatial locations to measure their dimensions.

Is it possible to cut in AutoCAD these short cylinders (like 24a.dxf) from my big original object (N24-N25.dxf )??

Still, I need to know how will AutoCAD measure the dimensions of my 3d solid model!

I just began using AutoCAD last few days !!

best,

Alsayed

[Anonymous]

 Thanks a lot for the kind response. 

[Anonymous]

Hi TheCADnoob,

I want to figure out how AutoCAD get the unit data from the files.

I want to measure volume, lateral surface area, and length of a 3D model which is cylinder in shape. I could measure the length and volume but still can not measure lateral surface area of the cylinder. Any tips?

I have no problems with units.

grateful,

sayed

[leeminardi · Accepted solution]

I converted the 24a 3dface model to a solid model by first using the command planesurf to convert the faces to planes. Once they are planes the command surfsculpt can be used to create a solid object if the planes encompass a "watertight" volume.  They do.

The solid model is on layer "solid" and I froze layer dendrite... in the attached file.

You can use massprop to give you the volume and other mass properties of a solid.  Try using area object to calculate the surface area of the solid.  I think you will need more experience to determine the other values you seek.    Get some more basic experience with AutoCAD and have an experienced user work with you if possible.

Good luck! 

[Anonymous]

Hi leeminardi,

Thanks a lot for that.

Now we could measure length, volume and the total area enclosed by my 3D solid. Is it possible to measure the lateral surface area only like in the attached photo?

grateful,

sayed

[john.vellek]

HI @Anonymous,

I believe the only way to do so would be to break that apart from the model. I made a copy first and then used explode. I moved the unwanted geometry from the copy and then used MASSPROP to get the region’s area.

[Anonymous]

Hi john.vellek,

Could you kindly elaborate on some steps I can follow to Explode the unwanted part of my solid object? As you know the surface area of the only lateral part of the cylinder wanted to be measured.

Thanks a lot,

sayed

john.vellek has embedded your image(s) for clarity

[john.vellek · Accepted solution]

Hi @alsayedvet84,

I made a quick (and rough) video that shows my process. You will see that I copy the model and then use EXPLODE. This results in regions.  I can then delete the ones I do not want to include in the analysis.  You will see that I accidentally deleted one too many so I had to go back and create a new region to replace it.  This is a pretty manual process but it actually goes pretty quickly.

Please select the Accept as Solution button if my post solves your issue or answers your question.