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Development of a simulator for airborne altimetric LiDAR


After this, to involve a little more complexity, two or more surfaces are stitched together:

    1. Stitching of two planes (Figure 2.4).
    The intersection of laser vector with both planes is taken and the higher value of Z is chosen and data points from corresponding plane are obtained.

    2. Inverted cone on horizontal surface (Figure 2.5).
    The intersection with cone is obtained similar to previously discussed cone except that, here altitude of the cone top is mentioned by user along with the reduced level of surrounding ground. If Z value obtained with the intersection of cone is less than that of ground reduced level, then intersection with the ground is sought.

    3. Hemisphere ( ) on horizontal ground (Figure 2.6).





    If D<0; it indicates no intersection with sphere and thus the intersection with
    ground surface is sought.
    else, , where R is the radius of hemisphere.

    4. Right Circular Cylinder on horizontal surface:


    If D<0: no intersection with cylinder, therefore Z is obtained by intersection with ground.

    else     

  • If Z&glt; Height of the cylinder, then actual point is either on top of cylinder or on ground, put Z= Height of the cylinder, obtain X and Y.

    If then point is on ground (obtain Z by intersection with ground) else Z= Height of the cylinder (On top of cylinder).

    If Z>ground RL and < Height of the cylinder, then point is either correct or at top of cylinder, put Z= Height of the cylinder. Obtain X and Y.

  • If then Z obtained before else Z= Height of the cylinder.

    If Z<ground RL: either point is on ground or at top of cylinder. put Z=Ht cyl. obtain X and Y.
  • If then point is on ground (obtain Z by intersection with ground) else Z= Height of the cylinder (On top of cylinder).

    5. Inverted cone/ hemisphere on top of cylinder placed on horizontal surface
    Intersection with cone/ hemisphere (Figure 2.7 and 2.8) is obtained similar to as explained before, but when Z obtained is less than or equal to cylinder height, the laser vector is solved with cylinder as discussed above.
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