Lidar system and method

1. A ground-based method of determining the spatial statistics of fragmented and spatially variably dispersed objects in a transmissive medium, said method including:

generating a plurality of pulsed beams of laser energy, said beams having selectively variable width and shape;

selectively varying the width and shape of said beams;

directing said beams toward the dispersed objects;

selectively varying the range and/or angle of scanninig;

measuring the time and/or phase and intensity of signals returned by the dispersed objects, and

calculating the apparent reflectance of the dispersed objects as a function of the range of the dispersed objects for each beam width and beam shape;

whereby the effects of object orientation are taken into account, and if the method surveys a forest and measures the spatial structure and cover of vegetation canopies in the forest, the effect of clumping of foliage and the effect of the angle of distribution of foliage are taken into account.

2. A ground-based method of determining the spatial statistics of fragmented and spatially variably dispersed objects in a transmissive medium as claimed in claim 1 , and including:

calibrating an instrument in accordance with the apparent reflectance calculated.

3. A ground-based system for determining the spatial statistics of fragmented and spatially variably dispersed objects in a transmissive medium, said system including:

Lidar means for generating a plurality of pulsed beams of laser energy having selectively variable width and shape, for selectively varying the width and shape of said beams, for directing said beams toward the dispersed objects, and for selectively varying the range and/or angle of scanning;

measuring means for measuring the time and/or phase and intensity of signals returned by the dispersed objects; and

calculating means for calculating the apparent reflectance of the dispersed objects as a function of the range of the dispersed objects for each beam width and beam shape;

whereby the system is calibrated in accordance with the apparent reflectance calculated, the effects of obiect orientation are taken into account, and if the method surveys a forest and measures the spatial structure and cover of vegetation canopies in the forest, the effect of clumping of foliage and the effect of the angle of distribution of foliage are taken into account.

4. A ground-based method of determining the spatial statistics of fragmented and spatially variably dispersed objects in a transmissive medium as claimed in claim 1 , wherein the method surveys a forest and measures the spatial structure and cover of vegetation canopies in the forest.

5. A ground-based system of determining the spatial statistics of fragmented and spatially variably dispersed objects in a transmissive medium as claimed in claim 3 , wherein the system surveys a forest and measures the spatial structure and cover of vegetation canopies in the forest.

6. A ground based method of surveying a forest as claimed in claim 4 , said method including:

taking into account the trade-off between scatterer density and reflectivity by the controlled variation of beam size and range, and by utilising a high sampling rate of return pulse intensity, a small pulse width and a suitable Signal to Noise Ratio.

7. A ground-based method of determining the spatial statistics of fragmented and spatially variably dispersed objects in a transinissive medium as claimed in claim 1 , wherein the method surveys an individual measure tree and derives statistical information relating thereto.

8. A ground-based system for determining the spatial statistics of fragmented and spatially variably dispersed objects in a transmissive medium as claimed in claim 3 , wherein the system surveys an individual measure tree and derives statistical information relating thereto.