Thank you Petr, I imagined from it not working that this must be the case. Unless I cannot understand correctly, the Wiki does not preclude software imaging from _MAPTRIANGLE(3D) - with z- coordinates - although the example given uses a hardware image. For Fellippe's information, this will be part of an InForm program, though I am merely investigating at the moment and have not used InForm here at the moment.
Would there be a reason why _MAPTRIAMGLE(3D) only works with hardware imaging? What the processor/graphics card produces is a 2D image, so the two things would not appear to be related, but this will be another thing beyond my comprehension.
Richard