# Intersecting geometry with already created mesh **URL:** \ **Category:** FLAC3D\ **Tags:** suggestions\ **Created:** [June 8, 2024, 12:35pm UTC](https://forum.itascainternational.com/t/intersecting-geometry-with-already-created-mesh/1510 "2024-06-08T12:35:31Z")\ **Posts on this page:** 11\ **Page:** 1
**Author:** ![Felipe](https://yyz1.discourse-cdn.com/flex031/user_avatar/forum.itascainternational.com/felipe/32/1095_2.png) [@Felipe](https://forum.itascainternational.com/u/Felipe)\ **Post date:** [June 8, 2024, 12:35pm UTC](https://forum.itascainternational.com/t/intersecting-geometry-with-already-created-mesh/1510/1 "2024-06-08T12:35:31Z")
Hi, I’ve already created a mesh in Griddle with 99 cuts of longwall panels. Since I need to create interfaces for their roofs, I want to import the mesh of the roofs into FLAC to create group faces and then proceed with interface creation. However, I’m not able to create the face groups from the mesh ‘roofs.dxf’. How do you proceed in such a case? The other solution is to separate the roofs in Rhino, assign them names, and griddle-mesh 3D all over again, but I don’t want to do that. ---
**Author:** ![msepu](https://avatars.discourse-cdn.com/v4/letter/m/b9e5f3/32.png) [@msepu](https://forum.itascainternational.com/u/msepu)\ **Post date:** [June 10, 2024, 2:00pm UTC](https://forum.itascainternational.com/t/intersecting-geometry-with-already-created-mesh/1510/2 "2024-06-10T14:00:35Z")
if you can identificate the groups between those roofs, the faces will have that group names and you can get those names to make interfaces ---
**Author:** ![Felipe](https://yyz1.discourse-cdn.com/flex031/user_avatar/forum.itascainternational.com/felipe/32/1095_2.png) [@Felipe](https://forum.itascainternational.com/u/Felipe)\ **Post date:** [June 10, 2024, 5:01pm UTC](https://forum.itascainternational.com/t/intersecting-geometry-with-already-created-mesh/1510/3 "2024-06-10T17:01:11Z")
That’s precisely the problem, Matias. Identifying those groups. The boundaries of the whole panels are like ‘IF\_001\_002’ (for example) and I only want the roof of these ones. Is there a quick way (one command or two) to get **only** the group face of the roofs? Maybe by using the geometry of the roofs? (which happens to be exactly the same as the one in FLAC3D) Thank you ---
**Author:** ![msepu](https://avatars.discourse-cdn.com/v4/letter/m/b9e5f3/32.png) [@msepu](https://forum.itascainternational.com/u/msepu)\ **Post date:** [June 10, 2024, 5:18pm UTC](https://forum.itascainternational.com/t/intersecting-geometry-with-already-created-mesh/1510/4 "2024-06-10T17:18:27Z")
if you have the zone groups ‘above roof’ and ‘below roof’ you can identify the faces with the range: range group ‘above roof’ group ‘below roof’, but if you can not get those groups, you’ll have to go back to griddle (no body wants that) ---
**Author:** ![Felipe](https://yyz1.discourse-cdn.com/flex031/user_avatar/forum.itascainternational.com/felipe/32/1095_2.png) [@Felipe](https://forum.itascainternational.com/u/Felipe)\ **Post date:** [June 10, 2024, 8:08pm UTC](https://forum.itascainternational.com/t/intersecting-geometry-with-already-created-mesh/1510/5 "2024-06-10T20:08:05Z")
I’m quite sure this should be doable with a variation of the command: `zone face group 'roof' range geometry-distance 'roof' gap 1` I was able to group some faces, but not the one I want. I tried gap 0 as well and I got the warning “+++ No face group assignments were changed” I’ve tried many gaps but still no roofs. Thanks ---
**Author:** ![msepu](https://avatars.discourse-cdn.com/v4/letter/m/b9e5f3/32.png) [@msepu](https://forum.itascainternational.com/u/msepu)\ **Post date:** [June 10, 2024, 8:12pm UTC](https://forum.itascainternational.com/t/intersecting-geometry-with-already-created-mesh/1510/6 "2024-06-10T20:12:52Z")
did you try “… gap 1 extent” ? ---
**Author:** ![msepu](https://avatars.discourse-cdn.com/v4/letter/m/b9e5f3/32.png) [@msepu](https://forum.itascainternational.com/u/msepu)\ **Post date:** [June 10, 2024, 8:14pm UTC](https://forum.itascainternational.com/t/intersecting-geometry-with-already-created-mesh/1510/7 "2024-06-10T20:14:10Z")
other way could be: zone group ‘bottom’ zone group ‘top’ range geomtry-space ‘roof’ count odd direction 0,0,-1 zone face group ‘roof’ range group ‘bottom’ group’ top ---
**Author:** ![Felipe](https://yyz1.discourse-cdn.com/flex031/user_avatar/forum.itascainternational.com/felipe/32/1095_2.png) [@Felipe](https://forum.itascainternational.com/u/Felipe)\ **Post date:** [June 10, 2024, 8:35pm UTC](https://forum.itascainternational.com/t/intersecting-geometry-with-already-created-mesh/1510/8 "2024-06-10T20:35:34Z")
I’ve tried extent, and it doesn’t give me anything. Just the warning. I tried your recommendations, but just like before, it gave me face groups in the boundaries of the external box, as it were projecting the ‘roof.dxf’ on the outer box, and not in the panel. But I think we’re close to accomplish the goal. ---
**Author:** ![msepu](https://avatars.discourse-cdn.com/v4/letter/m/b9e5f3/32.png) [@msepu](https://forum.itascainternational.com/u/msepu)\ **Post date:** [June 10, 2024, 8:49pm UTC](https://forum.itascainternational.com/t/intersecting-geometry-with-already-created-mesh/1510/9 "2024-06-10T20:49:41Z")
can you share us a face group plot? ---
**Author:** ![Felipe](https://yyz1.discourse-cdn.com/flex031/user_avatar/forum.itascainternational.com/felipe/32/1095_2.png) [@Felipe](https://forum.itascainternational.com/u/Felipe)\ **Post date:** [June 11, 2024, 7:48am UTC](https://forum.itascainternational.com/t/intersecting-geometry-with-already-created-mesh/1510/10 "2024-06-11T07:48:46Z")
Well the issue was solved, this a picture of ‘test’ model. ![image](https://canada1.discourse-cdn.com/flex031/uploads/itasca/original/2X/e/ea6b5999ed003185cbfe0b0e121c6a100414d4cb.png) If the geometry imported is exactly the same mesh as the one created by Griddle, you can try a gap equal to the mesh size of the geometry, with the command: > zone face group ‘roof’ internal range geometry-distance ‘roof’ gap 1 That gave me the wanted group but with some noise, so I had to apply the command again with a very low gap, to get the green wanted area, > zone face group ‘roof1’ internal range geometry-distance ‘roof’ gap 0.1 The ‘internal’ part of the code was the key. So it’s done. Hope this helps Thanks for you assistance, Matias. Best, Felipe ---
**Author:** ![paul](https://yyz1.discourse-cdn.com/flex031/user_avatar/forum.itascainternational.com/paul/32/196_2.png) [@paul](https://forum.itascainternational.com/u/paul)\ **Post date:** [August 30, 2024, 10:42am UTC](https://forum.itascainternational.com/t/intersecting-geometry-with-already-created-mesh/1510/11 "2024-08-30T10:42:41Z")
It’s always “internal”! 🤣 I can never get it right