The main purpose of the algorithm in this paper is to extract geometry information (mainly includes the plane function,
the outlines and the corners of the building surfaces) from the point cloud. The main process includes: filter and sort the
point cloud, get fitting lines in each column and merge the fitting lines, get fitting faces from the fitting lines and merge
the fitting faces, extract the outlines and corners of the merged faces. The advantage of the algorithm includes: A face's
adjacent faces can be got, the disturbing points can be automatically removed and the computation amount is relatively
small. The algorithm is particularly suit for the point cloud got by vehicle-borne laser scan.
An algorithm is proposed to calculate the left ventricular volume by the number of the filled pixel. Firstly, A closed
B-spline curve is used to show the left ventricle's each section outline, then we can fill the left ventricle and a regular
three dimension object whose volume is known at the same display mode, finally, the left ventricular volume can be got
by the ratio of the two objects' filled pixel numbers. When we fill the left ventricle, three methods are used. They are
methods to get the intersect points of a horizontal plane and
B-spline curves, to get the extremum point of a B-spline
curve, and to fill a closed B-spline curve. Taking results from CMRI as reference, it is showed that the algorithm in this
paper is more valid and reliable than that of COMPACT4.2.