Using solids in C3d

[db41028]

I have a drawing (c3d 2013) provided by a subcontractor that contains high density laser scan data in the form of Acad solids. I have a bunch of conventional QC shots on the same objects, that I would like to compare to the scan data. I can bring the QC shots into the scan drawing as cogo points, but when I try to measure the distance to the face of  the solid, I can't get the perpendicular 3d osnap to grab the solid. Do I have a system variable set wrong, or does anyone have another method that would work?

[jmayo-EE]

Explode the solids. If you need to retain them, copytolayer and explode the copies.

If you are trying the OSNAP is a 3dview that is not 2dwireframe, try changing it to 2dwireframe and see if snap works.

Make sure you do not have duplicate geometry under the solids. If you do turn off those layers so the snap sees the 3d objects first.

This is really quick of the top of my head, so start at the bottom of this list and work up for best results. 🙂

[db41028]

Nothing in the drawing except the solids & the points that I am trying to compare. Changing to 2d wireframe didn't seem to help, but does make it easier to see stuff in the drawing, so thanks for that. Exploding the solids turns each face into a region, I can 2d snap to the edges of each regoin, but not to the face.

I've added a screengrab to show what I'm up against. The point is the QC shot I'm trying to compare, it's basically in the middle of a big concrete peir, so I would need to snap to 3d perp. closest to the point. I seem to be able to snap to the opposate side, but not the close side. When I do a 3d orbit so that the point is obscured by the solid, I can sometimes snap to the correct side, but that makes it pretty difficult to snap to the point node. Top view might work, but has a similar problem, there are thousands of solids in the way of seeing what I am snapping to.

I'm going to try thinning the drawing out to just the stuff I'm trying to compare to unless someone has a better idea.

Thanks!

[db41028]

No luck there either. I tried erasing all the solids around the one I'm working on, then going to top view. It will snap to a perp. point, but it isn't the one closest to the point, and from the top view I can't really tell what it's snapping to as I work. I can draw a line from the point node to perp, but when I list the line it's a few thousandths in length horizontally, but a 3d length of several feet, obvously it snapped to the edge above or below the point.

[tcorey]

Turn on 3DOsnap and check that the Center of Face option is turned on in settings.

Invoke the Distance command. Pick the node of your point for the first point then, when it asks for next point, point to the face. You might have to move around a little, but eventually you'll see a blue circle show up and a tooltip saying 3D Center.

Tim

[AllenJessup]

The center of face osnap should work. If you still have trouble. You can draw a line from the midpoint of the top of the pier to the midpoint of the bottom. The midpoint of that line will be close to the center of that face. The accuracy will depend on how warped the face is. In the picture you posted it looks fairly regular.

Allen Jessup

[troma]

Not to be a spoilsport, but the centre of the face is not the same as the point on the face closest to the cogo point.  The point closest to the cogo point is found by drawing a line from the cogo point perpendicular to the face, until it intersects the face.

I haven't got any bright ideas, just raining on your parade, sorry. 

[db41028 · Accepted solution]

Quite right troma, the cogo points are not necessarily at the center of the face. The field crew just shot what they could see from a each control point with a reflectorless EDM.

I think I have found a solution though. By switching to the 2d wireframe view, I can see through each object. If I 3d orbit so that the solid is between my perspective and the cogo point, I am able to get the 3d perp snap to grab the correct face. In other words the 3d perp snap only seems to work away from the view perspective (the 'camera' point).

Poorly described by me, but bottom line problem solved, thanks for the help everyone!

[tcorey]

Sorry, I didn't read your OP closely enough. You did say the nearest point on the face, so center of face won't work. It sounds like you have a good solution using 3dosnap, though.