I Need Help On Surface Modeling, AutoCAD 2002

[spinecad]

Can anyone help me how to model these 3 curves so that I can get a surface such as the attached images in AutoCAD 2002?

surfacemodeling.dwg

[mikekmx]

not me, but beautiful drawings you have there

[SEANT]

You will need a lot of patience and determination if you intend to model this accurately in 2002. That version of AutoCAD lacks a lot of the surface modeling capabilities of AutoCAD 2007+.

 

 

 

I think the best method for that particular surface would be the EdgeSurf Command. Look in the help files for that command, as well as SurfTab1 and SurfTab2 system variables.

 

 

 

Also, for a more accurate surface, two curves – from Top and Back– should be included at the bumper line. In the attached, I just copied your curve from the top view down to the bumper line position.

 

 

 

The 3DSpline was made by trimming construction lines – made by dividing the top view curve, creating drop lines and trimming from the Right view.

surfacemodelVia2002.dwg

[f700es]

I am going to agree with SeanT. I recently completed a project in 2013 using some curve tools and I would have hated to have tried that in 2002. What program are those images from?

[f700es]

Took a quick shoot and here is what I got. Used only 2 commands, Spline CV and Network Surface. Yeah, pretty messy but doable.

Splines could have been done better but it was quick and dirty.

 

[spinecad]

You will need a lot of patience and determination if you intend to model this accurately in 2002. That version of AutoCAD lacks a lot of the surface modeling capabilities of AutoCAD 2007+.

 

 

 

I think the best method for that particular surface would be the EdgeSurf Command. Look in the help files for that command, as well as SurfTab1 and SurfTab2 system variables.

 

 

 

Also, for a more accurate surface, two curves – from Top and Back– should be included at the bumper line. In the attached, I just copied your curve from the top view down to the bumper line position.

 

 

 

The 3DSpline was made by trimming construction lines – made by dividing the top view curve, creating drop lines and trimming from the Right view.

 

Can you tell me step-by-step how to do it?

[SEANT]

I don't have the any version of AutoCAD prior to 2012, so I'd have to go by memory. What procedure is giving you trouble?

 

Your signature says you have AutoCAD 2012 available, what you're trying to do would be far easier in that version of AutoCAD.

[spinecad]

I don't have the any version of AutoCAD prior to 2012, so I'd have to go by memory. What procedure is giving you trouble?

 

EdgeSurf Command, SurfTab1, and SurfTab2 system variables

 

I need to know the step how the surface in #3 was made in AutoCAD 2002 by using the available three curves.

 

[SEANT]

I’ll take this step by step – that way if I have made a mistake in what was available in 2002, it will be quite obvious.

 

Given the symmetry, the first suggestion I would make is to trim the “Top View” to eliminate everything above Point D. Similary, trim the “Back View” curve.

 

The drawing surfacemodel.dwg current has geometry from all three views aligned with the top view. The Back and Side views need to be realigned. With the ROTATE3D command, align the “Back view” geometry (Please review the ROTATE3D command in the Help file). Start the command, select all of the geometry (and the labels), select point A, then point B. Input 90 when the angle is requested.

 

Now, while still in the Top view (World Coordinate System), use the standard ROTATE command to rotate the same selection of entities -90 degrees around point A. Finally move the entities so that Point C is positioned at Point D.

Use a similar approach to position the “Side View”.

 

Look at the drawing surfacemodelVia2002.dwg to see how the final position should look – you will be able to figure out how the “Side View” should be rotated.

 

Let me know when we should proceed.

surfacemodelTute.dwg

[spinecad]

I’ll take this step by step – that way if I have made a mistake in what was available in 2002, it will be quite obvious.

 

Given the symmetry, the first suggestion I would make is to trim the “Top View” to eliminate everything above Point D. Similary, trim the “Back View” curve.

 

The drawing surfacemodel.dwg current has geometry from all three views aligned with the top view. The Back and Side views need to be realigned. With the ROTATE3D command, align the “Back view” geometry (Please review the ROTATE3D command in the Help file). Start the command, select all of the geometry (and the labels), select point A, then point B. Input 90 when the angle is requested.

 

Now, while still in the Top view (World Coordinate System), use the standard ROTATE command to rotate the same selection of entities -90 degrees around point A. Finally move the entities so that Point C is positioned at Point D.

Use a similar approach to position the “Side View”.

 

Look at the drawing surfacemodelVia2002.dwg to see how the final position should look – you will be able to figure out how the “Side View” should be rotated.

 

Let me know when we should proceed.

 

We can proceed to the next step.

[SEANT]

Use the DIVIDE command on the “Top View”, at the “Enter the number of segments” prompt, enter 8.

 

AutoCAD will place 7 evenly spaced points along the curve (to essentially divide the curve into 8 sections). You may not be able to see the points: If so, Enter PDMODE at the command prompt and input 66.

 

 

 

Add a line, start point at D, and, when the prompt says “Specify next point”, type

 

@0,0,-500

 

 

 

Copy that line to each of the points – using the NOD osnap –as well as to the end of the curve.

 

 

 

Rest the UCS and View to RIGHT SIDE, then use the TRIM command, with the “Back View” curve as trimming entity, to trim the lower portions of each line.

[spinecad]

 

Copy that line to each of the points – using the NOD osnap –as well as to the end of the curve.

 

 

 

Rest the UCS and View to RIGHT SIDE, then use the TRIM command, with the “Back View” curve as trimming entity, to trim the lower portions of each line.

 

I don't understand.

 

Can you explain it using illustration?

 

Meanwhile, please see the attached image to check whether I am doing wrong or not.

[SEANT]

I’ll be direct:

 

This endeavor is extremely complex. Quite probably, you are the last person in existence that will ever be remotely interested in doing this in AutoCAD2002. I can only afford to devote so much effort into this tutorial. Should we decide to proceed, the vast majority of the effort applied to learning this process will be yours.

 

Undoubtedly, that statement makes me sound like an a-hole; it is the grim reality.

 

 

 

Everything I’ve described so far is represented graphically in the 2 drawings attached to Posts #3 and #9. Re-read everything we’ve got so far and review those drawings. In the post #3 drawing, the pertinent geometry has been rotated to its appropriate position, the "@0,0,500" lines copied to the NOD positions are already trimmed.

 

 

 

Post your drawing to show that we are ready to proceed.

[spinecad]

This is the drawing.

 

I had rotated them.

 

All of the three curves are shown as red.

surfacemodelingrotation.dwg

[SEANT]

That is incorrect. You should probably start over.

 

See the screen cast here:

http://screencast.com/t/44fkKH5YqR

 

and compare it to the list of steps I described in post #9. Also, compare it to the file I attached to post #3.

[spinecad]

That is incorrect. You should probably start over.

 

See the screen cast here:

http://screencast.com/t/44fkKH5YqR

 

and compare it to the list of steps I described in post #9. Also, compare it to the file I attached to post #3.

 

OK, now the position of the two curves had been corrected similar as shown as above video.

 

What next?

surfacemodelingrotation2.dwg

[spinecad]

Also, I use the edgesurf command.

 

Select object 1 for surface edge = back-view curve

 

Select object 2 for surface edge = side-view curve

 

Select object 3 for surface edge = top-view curve

 

I press enter and nothing happen.

surfacemodelingrotation3.dwg

[SEANT]

You should now pick up at post # 11. The “Top View” and “Back View” curves are the orthographic projection of a 3D curve. The curves have to be analyzed and sub-divided to recreate the 3d curve. See the drawing in Post #3 (Move the surface out of the way to get a better look).

 

Also note in my reply to post #3, I mentioned that the original 3 curves are not enough to recreate that surface accurately. You also need these curves.

[spinecad]

How to do this?

surface modeling.dwg

[SEANT]

This, maybe?

 

Lofted the four perimeter curves with the lower elliptical spline as a Guide.

 

 

The profiles are a bit ambiguous, though - tough to say what is required.

surface modeling.dwg