# How to compute intersections between NURBS and lines

**URL:** <https://forum.techsoft3d.com/t/how-to-compute-intersections-between-nurbs-and-lines/682>\
**Category:** HOOPS Visualize Desktop\
**Tags:** code\
**Created:** [March 7, 2022, 10:34pm UTC](https://forum.techsoft3d.com/t/how-to-compute-intersections-between-nurbs-and-lines/682 "2022-03-07T22:34:26Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![qcui](https://avatars.discourse-cdn.com/v4/letter/q/898d66/32.png) [@qcui](https://forum.techsoft3d.com/u/qcui)\
**Post date:** [March 7, 2022, 10:34pm UTC](https://forum.techsoft3d.com/t/how-to-compute-intersections-between-nurbs-and-lines/682/1 "2022-03-07T22:34:26Z")

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Hi, I have an application where I need to find the intersections between a ray and a NURBS surface. How do I compute that.

Thanks.

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**Author:** ![jeff.wheeler](https://avatars.discourse-cdn.com/v4/letter/j/e274bd/32.png) [@jeff.wheeler](https://forum.techsoft3d.com/u/jeff.wheeler)\
**Post date:** [March 8, 2022, 11:04pm UTC](https://forum.techsoft3d.com/t/how-to-compute-intersections-between-nurbs-and-lines/682/2 "2022-03-08T23:04:43Z")

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Hi Qiaodong, to make sure we give you the best answer, are you looking to compute intersections between several different geometry with-in the model and a NURBS Surface or a ray outside of the geometry that returns all NURBS surfaces that intersect with that ray?

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**Author:** ![qcui](https://avatars.discourse-cdn.com/v4/letter/q/898d66/32.png) [@qcui](https://forum.techsoft3d.com/u/qcui)\
**Post date:** [March 9, 2022, 12:07am UTC](https://forum.techsoft3d.com/t/how-to-compute-intersections-between-nurbs-and-lines/682/3 "2022-03-09T00:07:54Z")

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Thanks for replying. Ideally I want to raycast a Brep model that could contain NURBS surfaces, and find all intersections of the ray with the Brep model. Raycasting a triangle mesh is easy, but I’m not sure if HPS can handle ray intersections with Brep like NURBS.

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**Author:** ![jeff.wheeler](https://avatars.discourse-cdn.com/v4/letter/j/e274bd/32.png) [@jeff.wheeler](https://forum.techsoft3d.com/u/jeff.wheeler)\
**Post date:** [March 14, 2022, 4:45pm UTC](https://forum.techsoft3d.com/t/how-to-compute-intersections-between-nurbs-and-lines/682/4 "2022-03-14T16:45:29Z")

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Hi QCui, in Visualize, our cross platform 3d visualization SDK has a way to check for selection on different parts of model effectively casting a ray through the model and returning a list of things it intersects with, but does not provide for direct high performance NURBS surface ray casting.