stairs- again

[Ziska]

Double posting this to 3D and renderworks as the two issues seem linked

for images:

http://techboard.nemetschek.net/ubb/ultimatebb.php?ubb=get_topic;f=17;t=000513;p=1#000000

Stair on a volute- which needs the two square tube supports drawn:

Image 1 shows the rise- and where the support needs to hit each tread- it's in

artistic render mode.

Image 2 shows the support in artistic render mode- unfortunately this is 4 nurbs surfaces -created from polylines in plan and then reshaped as a 3D poly in elevation then "renurbed"- to get this as a single object would be nice (haven't a clue- tried loft, 3D poly's , add solids, fillet, I'm stymied- all suggestions welcome)

Image 3 shows the same as image 2 in final renderworks mode- a fairly unimpressive sight....

[tom kyler_dup1]

Ziska, this is variation of the method mentioned by Lamberto in the renderworks forum, but a bit more reliable than using sections. I didn't have you exact dimensions so I just made some up. You can see from the plan view that I have different radii for the outside and inside of the treads as well as different radii for each of the supports. I figured this was a worst case (except variable height treads) and would demonstrate the technique adequately.

The general idea is to create 3D loci as ?dots? and then connect the dots to give you a nurbs curve to begin your supports. I placed 2D loci at the intersection between supports and treads (see upper right image) and then placed 3D loci on top of the 2D loci. ( I did this because the 3D loci wouldn't snap to the intersection but would snap to a 2D locus) Now the actual intersection between tread and support might not be at the edge of the tread like I've done, but you can make adjustments easily by shifting the treads after the model is created, the important thing being that the vertical distance between tread and support is consistent the entire run of the stairs.

Now you should inlcude some extra 3D loci ?extensions? on each end of the run to maintain continuity of the support. Of course the extensions at the beginning of the run would continue below the level of the floor. You can trim the support later.

Once I had my 3D loci, I used the 3D move command and moved the loci up 8? at a time. Once all the loci were in place (in 3D space). I used the nurbs tool to connect the dots. So at this point I have two nurbs curved in 3D space. I then go to a orthographic view (front or side) and then duplicate both nurbs curves vertically ...I think I duplicated them 10?. Now you can use the loft tool and loft the top curve to the bottom curve (x2) and you'll have two nurbs surfaces. Then use the shell tool to add some thickness to your supports. I used 1 1/2?. Now when you begin moving your extruded treads up 8? at a time, the'll exactly lie on the support all the way up the supports. Then you can move them up or down to put them ?into? or above the support. At that point, you can trim the top and bottom and you should be pretty close to where you want to be.

I added some triangle supports at the bottom just to give them some extra beef.

[ 09-19-2004, 02:55 PM: Message edited by: tom kyler ]