rendering - Simple volume ray casting -

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the question might simple, realize answer may not be. keep clear possible.

can explain basic idea volume ray casting technique in 3d volume rendering.

cheers, timo

this reference presents reasonable introduction simple raycasting link. concepts (ray-plane intersections, etc) can extended volume ray casting link.

to summarize, ray cast through volume , accumulates color each intersection meets criteria. example, each voxel along ray possessing value > 128 might contribute small percentage of opacity desired rgb color. degree of opacity weighted, (voxel_value - 128)/127 might suitable weighting function in simplified case (assuming negative values handled appropriately). scheme represent proportional, thresholded transfer function. rendering, pixel associated ray assigned color determined summed opacities encountered along path. (this front-to-back alpha blending - other methods exist.)

other transfer functions exist, well: functions might weight gradients heavily. sort of function might used visualize surface boundaries occurring within volume.

i recommend vtk books further reading.


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