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Improved height interpolation for bad points near cliffs.

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The original algorithm looked for good heights at the corners
of the rectangle with the target point at the centre. This fails
in pathological cases where only a single good point is available
in a non-corner position.
This commit is contained in:
James.Hester 2020-01-28 19:52:54 +11:00
parent 6807638af1
commit cce218627b
1 changed files with 24 additions and 4 deletions
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28
src/Lib/Array/array.cxx
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@ -517,7 +517,9 @@ double TGArray::rectify_point(const int xgrid, const int ygrid, const std::vecto
//ygrid: grid units vertically
//Loop over corner points, if no points available, give up
int corners[4][2]; //possible corners
int sides[4][2]; //possible sides
int pt_cnt = 0;
int side_cnt = 0; //how many side points
double centre_long, centre_lat;
int original_height = get_array_elev(xgrid,ygrid);
centre_long = (originx + col_step*xgrid)/3600;
@ -538,10 +540,22 @@ double TGArray::rectify_point(const int xgrid, const int ygrid, const std::vecto
corners[pt_cnt][1] = vert;
pt_cnt++;
}
if ( !is_bad_point( xgrid+horiz,ygrid,bad_points ) && //can trust height
check_points( test_long,centre_lat,centre_long,centre_lat ) ) { //same side
sides[side_cnt][0] = horiz;
sides[side_cnt][1] = 0;
side_cnt++;
}
if ( !is_bad_point( xgrid,ygrid+vert,bad_points ) && //can trust height
check_points( centre_long,test_lat,centre_long,centre_lat ) ) { //same side
sides[side_cnt][0] = 0;
sides[side_cnt][1] = vert;
side_cnt++;
}
}
} // end of search for corners
if (pt_cnt == 0) return -9999; // no corners found
if ((pt_cnt == 0 ) && (side_cnt == 0)) return -9999; // no neighbouring good points
// Find two points that form a rectangle with a corner
int pt;
@ -563,12 +577,18 @@ double TGArray::rectify_point(const int xgrid, const int ygrid, const std::vecto
// perhaps we have a concave cliff, just take the
// average of the known points
double totht = 0;
for( int pti = 0; pti <pt_cnt; pti++ ) {
if (pt > 0) { // corner points available
for( int pti = 0; pti <pt_cnt; pti++ ) {
totht = totht + get_array_elev( xgrid+corners[pti][0],ygrid+corners[pti][1] );
}
height = totht/pt_cnt;
} else {
for( int pti = 0; pti <side_cnt; pti++ ) {
totht = totht + get_array_elev( xgrid+sides[pti][0],ygrid+sides[pti][1] );
}
height = totht/side_cnt;
}
height = totht/pt_cnt;
} else {
// We have three points, calculate the height