/*!
* boxOverlapFraction()
*
* Input: box1, box2 (two boxes)
* &fract (<return> the fraction of box2 overlapped by box1)
* Return: 0 if OK, 1 on error.
*
* Notes:
* (1) The result depends on the order of the input boxes,
* because the overlap is taken as a fraction of box2.
*/
l_int32
boxOverlapFraction(BOX *box1,
BOX *box2,
l_float32 *pfract)
{
l_int32 w2, h2, w, h;
BOX *boxo;
PROCNAME("boxOverlapFraction");
if (!pfract)
return ERROR_INT("&fract not defined", procName, 1);
*pfract = 0.0;
if (!box1)
return ERROR_INT("box1 not defined", procName, 1);
if (!box2)
return ERROR_INT("box2 not defined", procName, 1);
if ((boxo = boxOverlapRegion(box1, box2)) == NULL) /* no overlap */
return 0;
boxGetGeometry(box2, NULL, NULL, &w2, &h2);
boxGetGeometry(boxo, NULL, NULL, &w, &h);
*pfract = (l_float32)(w * h) / (l_float32)(w2 * h2);
boxDestroy(&boxo);
return 0;
}
/*!
* boxaClipToBox()
*
* Input: boxas
* box (for clipping)
* Return boxad (boxa with boxes in boxas clipped to box),
* or null on error
*
* Notes:
* (1) All boxes in boxa not intersecting with box are removed, and
* the remaining boxes are clipped to box.
*/
BOXA *
boxaClipToBox(BOXA *boxas,
BOX *box)
{
l_int32 i, n;
BOX *boxt, *boxo;
BOXA *boxad;
PROCNAME("boxaClipToBox");
if (!boxas)
return (BOXA *)ERROR_PTR("boxas not defined", procName, NULL);
if (!box)
return (BOXA *)ERROR_PTR("box not defined", procName, NULL);
if ((n = boxaGetCount(boxas)) == 0)
return boxaCreate(1); /* empty */
boxad = boxaCreate(0);
for (i = 0; i < n; i++) {
boxt = boxaGetBox(boxas, i, L_CLONE);
if ((boxo = boxOverlapRegion(box, boxt)) != NULL)
boxaAddBox(boxad, boxo, L_INSERT);
boxDestroy(&boxt);
}
return boxad;
}
l_float32 ComputePairNormalizedOverlapArea(BOX *b1, BOX *b2) {
BOX *overlap = boxOverlapRegion(b1, b2);
if (!overlap || overlap->w == 0.0 || overlap->h == 0.0) return 0.0;
l_float32 area0 = overlap->w * overlap->h;
l_float32 area1 = b1->w * b1->h;
l_float32 area2 = b2->w * b2->h;
l_float32 oarea = 2.0 * area0 / (area1 + area2);
return oarea;
}
