
INTRODUCTION TO LASER SCANNING MICROSCOPY
LSM 510 Functions
B 40-051 e 07/98 5-63
Render - Alpha: Method Description
Each Output pixel is a weighted sum of the Input voxels along a ray in view direction through the Input
sequence. Each Input voxel has an opacity value, dependent only on its grey value. The opacity values
are defined by the parameters Threshold, Ramp, and Max. Opacity.
Accumulation of pixels proceeds along the ray from back to front, i.e. from far pixels to near pixels. If a
new pixel is added, it increases the result intensity by its grey value weighted by the opacity value, and
attenuates the previously accumulated intensity according to the opacity value. Full intensity stops
accumulation.
This calculation must be repeated for each pixel of the ray to generate one Output pixel. Then for each
Output pixel to produce a 2D Output image for the selected view-angle. Then for each view-angle to
produce an output sequence for Number of Views different view angles.
Render - References
[1] J.D. Foley,A.van Dam, S. K. Feiner, J.F.Hughes, Computer Graphics: Principles and Practice, Addison
Wesley, Reading, MA, 1990.
[2] M. Levoy, Display of Surfaces from Volume Data, IEEE Computer Graphics & Applications, May 1988,
29-37.
[3] J. Ylä-Jääski, F.Klein, O. Kübler, Fast Direct Display of Volume Data for Medical Diagnosis,
VGIP:Graphical Models and Image Processing 53,1991,7-18.
[4] K.H. Höhne, R. Bernstein, Shading 3D-Images from CT Using Gray-Level Gradients, IEEE Transactions
on Medical Imaging, 5, 1986, 45-47.
[5] D.Gordon, R.A. Reynolds, Image Space Shading of 3-Dimensional Objects, CVGIP 29, 1985, 361-376.
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