Some viewing frustums are bounded by hither and yon planes.
The HOOPS https://docs.techsoft3d.com/hps/latest/build/prog_guide/0303_cameras.html (3DF https://docs.techsoft3d.com/3df/latest/build/prog_guide/3dgs/03_2_viewing_modelling_cameras.html ) use “near limit” which is akin to hither and specifies the position of the view frustum near clipping plane. The near limit (nl) is a parametric value from 0 to 1 between the camera position (i.e. nl = 0.0) and the target (i.e. nl = 1.0).
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Further details:
SetNearLimit()https://docs.techsoft3d.com/hps3df/latest/build/apiprog_refguide/cpp3dgs/class03_h2_pviewing_s_1_1_camera_control.html#aa4be3d00e8b8dbd2450d0bc4163660ecmodelling_cameras.html (HPS)HC_Set_Camera_Near_Limit()https://docs.techsoft3d.com/3df/latest/build/api_ref/3dgs/hcHC_Set_Camera_protoNear_8hLimit.html#ae7ef5cad07b749152045d1f7fb652ea9html?h (3DF)