Square Facets On Sphere Modeling Challenge

[mgajewski]

Hi

 

I'd like to model a surface or a solid with square facets on a slice of a sphere as shown in the attached picture.

 

I am not sure how to best approach this and would appreciate any help.

 

Thanks!

 

Mark

[IronKevin]

Here's a Boolean approach. I'll leave you with the tedious task for positioning each "cut" tool part around the dome.

[mgajewski]

Hi Kevin,

 

Sorry I don't mean to be ungrateful but that solution seems pretty close to self-flagellation to me

 

I was hoping for some devilishly clever trick. I know this is a real challenge.

 

Mark

[IronKevin]

I'll let you know if I think of a better way.

sf.ics

[tlehnhaeuser]

Hi Kevin,

 

Sorry I don't mean to be ungrateful but that solution seems pretty close to self-flagellation to me

 

I was hoping for some devilishly clever trick. I know this is a real challenge.

 

Mark

18785[/snapback]

 

 

Mark,

I think you should be able to :

1. Create the dome shape

2. Drag a square block to its center and position close to top tangency

3. Extrude a custom shape that is tangent to dome and connects at end points of square (i.e 1"square then the bottom points intersect dome). Extrude 1" to complte a square shape.

4. Measure the angle distance from point to point (intersectiobs). Lets say angle is 5.4 degrees for argument sake then.

6. Create a rotational pattern with number of copies and angle at 5.4 degrees.

7. Then creat same pattern 90degrees .

 

Hope this makes sense. If I get time I will try to do it in reality.

Tom

[Robert Andersson]

I miss some info,

-Witch detail level do you want on the facets?

Do you want exact dimensional values on each facet?

If so, witch values?

-Can you use Export As STL and import?

-Will you do a 2D drawing of this or only a good looking rendering?

[Bernd Meißner]

I was hoping for some devilishly clever trick. I know this is a real challenge.

18785[/snapback]

 

 

It should be quite simple. All you need is a piece of facetted geometry, which can be done like this:

 

1. add a sphere (which *is* a revolved sphere and contains the facets you want)

2. export this sphere to *.OBJ format (facetted geometry, which retains quad faces instead of triangulating them)

3. re-import this OBJ file (which still is a solid you can use boolean tools on)

4. cut the portion you need (from the sides, not top or bottom)

5. difference a smaller sphere from the rest.

 

Attached is a file I created using an other application (which directly supports facetted geometry, without using the ex-/import route), but in IC it should work exactly as described above :-)

 

Bernd

FacettedSphere.ics

[dhovatter]

How about this one.

Dallas

[mgajewski]

I miss some info,

-Witch detail level do you want on the facets?

Do you want exact dimensional values on each facet?

If so, witch values?

-Can you use Export As STL and import?

-Will you do a 2D drawing of this or only a good looking rendering?

18789[/snapback]

 

I've tried the STL export/import trick but that did not produce square facets.

I'd like square facets as shown in my attached picture. This is for a rendering/appearance purposes only so I do not really need perfect dimensional accuracy but just a convincing picture at 300dpi at 8.5 x 11 inches.

 

Mark

[mgajewski]

I miss some info,

-Witch detail level do you want on the facets?

Do you want exact dimensional values on each facet?

If so, witch values?

-Can you use Export As STL and import?

-Will you do a 2D drawing of this or only a good looking rendering?

18789[/snapback]

 

I take it back, Robert - your idea worked pretty well. Thanks!

Mark

[mgajewski]

It should be quite simple. All you need is a piece of facetted geometry, which can be done like this:

 

1. add a sphere (which *is* a revolved sphere and contains the facets you want)

2. export this sphere to *.OBJ format (facetted geometry, which retains quad faces instead of triangulating them)

3. re-import this OBJ file (which still is  a solid you can use boolean tools on)

4. cut the  portion you need (from the sides, not top or bottom)

5. difference a smaller sphere from the rest.

 

Attached is a file I created using an other application (which directly supports facetted geometry, without using the ex-/import route), but in IC it should work exactly as described above :-)

 

Bernd

18810[/snapback]

 

Bernd, I could not get this to work. It got reimported without well-defined facets. Thanks! Mark

[mgajewski]

Mark,

I think you should be able to :

1. Create the dome shape

2. Drag a square block to its center and position close to top tangency

3. Extrude a custom shape that is tangent to dome and connects at end points of square (i.e 1"square then the bottom points intersect dome). Extrude 1" to complte a square shape.

4. Measure the angle distance from point to point (intersectiobs). Lets say angle is 5.4 degrees for argument sake then.

6. Create a rotational pattern with number of copies and angle at 5.4 degrees.

7. Then creat same pattern 90degrees .

 

Hope this makes sense. If I get time I will try to do it in reality.

Tom

18788[/snapback]

 

Tom, I don't think this will work if I follow you correctly. Only the blocks on the centerlines of the dome would behave correctly. Thanks! Mark

[Bernd Meißner]

Bernd, I could not get this to work. It got reimported without well-defined facets. Thanks! Mark

18834[/snapback]

 

 

Well, I just tried to to repeat what seemed to work yesterday (I was sure that I ex-/imported a sphere successfully), but today the results confirm your lack of success. Interesting enough: if I import the (OBJ) sphere I created in IronCad into FormZ, it arrives there as a perfect, facetted solid. Doing the same in IC leads to a facet part, which either has the facets required but is not a solid, or, after converting to a solid, has some triangulated facets. Not what it should be in my opinion...

 

Bernd

[Cary OConnor]

If it is only for rendering purposes, you can do this with an image and the bumps. Attached is a start of a sample....

 

I used the BlueGrid in the IronCAD images. Set the mapping to Spherical. Made the Bumps High.

 

Grid.BMP

 

As you can see you just need to find a nice image that will produce the smooth results you want from Google Images. Some sort of sqaure grid with soft lines (easily created in Photoshop).

 

Let me know.

Thanks

Cary