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#include "precomp.hpp"
/****************************************************************************************\
* Chain Approximation *
\****************************************************************************************/
typedef struct _CvPtInfo
{
CvPoint pt;
int k; /* support region */
int s; /* curvature value */
struct _CvPtInfo *next;
}
_CvPtInfo;
/* curvature: 0 - 1-curvature, 1 - k-cosine curvature. */
CvSeq* icvApproximateChainTC89( CvChain* chain, int header_size,
CvMemStorage* storage, int method )
{
static const int abs_diff[] = { 1, 2, 3, 4, 3, 2, 1, 0, 1, 2, 3, 4, 3, 2, 1 };
cv::AutoBuffer<_CvPtInfo> buf(chain->total + 8);
_CvPtInfo temp;
_CvPtInfo *array = buf, *first = 0, *current = 0, *prev_current = 0;
int i, j, i1, i2, s, len;
int count = chain->total;
CvChainPtReader reader;
CvSeqWriter writer;
CvPoint pt = chain->origin;
CV_Assert( CV_IS_SEQ_CHAIN_CONTOUR( chain ));
CV_Assert( header_size >= (int)sizeof(CvContour) );
cvStartWriteSeq( (chain->flags & ~CV_SEQ_ELTYPE_MASK) | CV_SEQ_ELTYPE_POINT,
header_size, sizeof( CvPoint ), storage, &writer );
if( chain->total == 0 )
{
CV_WRITE_SEQ_ELEM( pt, writer );
return cvEndWriteSeq( &writer );
}
cvStartReadChainPoints( chain, &reader );
temp.next = 0;
current = &temp;
/* Pass 0.
Restores all the digital curve points from the chain code.
Removes the points (from the resultant polygon)
that have zero 1-curvature */
for( i = 0; i < count; i++ )
{
int prev_code = *reader.prev_elem;
reader.prev_elem = reader.ptr;
CV_READ_CHAIN_POINT( pt, reader );
/* calc 1-curvature */
s = abs_diff[reader.code - prev_code + 7];
if( method <= CV_CHAIN_APPROX_SIMPLE )
{
if( method == CV_CHAIN_APPROX_NONE || s != 0 )
{
CV_WRITE_SEQ_ELEM( pt, writer );
}
}
else
{
if( s != 0 )
current = current->next = array + i;
array[i].s = s;
array[i].pt = pt;
}
}
//assert( pt.x == chain->origin.x && pt.y == chain->origin.y );
if( method <= CV_CHAIN_APPROX_SIMPLE )
return cvEndWriteSeq( &writer );
current->next = 0;
len = i;
current = temp.next;
assert( current );
/* Pass 1.
Determines support region for all the remained points */
do
{
CvPoint pt0;
int k, l = 0, d_num = 0;
i = (int)(current - array);
pt0 = array[i].pt;
/* determine support region */
for( k = 1;; k++ )
{
int lk, dk_num;
int dx, dy;
Cv32suf d;
assert( k <= len );
/* calc indices */
i1 = i - k;
i1 += i1 < 0 ? len : 0;
i2 = i + k;
i2 -= i2 >= len ? len : 0;
dx = array[i2].pt.x - array[i1].pt.x;
dy = array[i2].pt.y - array[i1].pt.y;
/* distance between p_(i - k) and p_(i + k) */
lk = dx * dx + dy * dy;
/* distance between p_i and the line (p_(i-k), p_(i+k)) */
dk_num = (pt0.x - array[i1].pt.x) * dy - (pt0.y - array[i1].pt.y) * dx;
d.f = (float) (((double) d_num) * lk - ((double) dk_num) * l);
if( k > 1 && (l >= lk || ((d_num > 0 && d.i <= 0) || (d_num < 0 && d.i >= 0))))
break;
d_num = dk_num;
l = lk;
}
current->k = --k;
/* determine cosine curvature if it should be used */
if( method == CV_CHAIN_APPROX_TC89_KCOS )
{
/* calc k-cosine curvature */
for( j = k, s = 0; j > 0; j-- )
{
double temp_num;
int dx1, dy1, dx2, dy2;
Cv32suf sk;
i1 = i - j;
i1 += i1 < 0 ? len : 0;
i2 = i + j;
i2 -= i2 >= len ? len : 0;
dx1 = array[i1].pt.x - pt0.x;
dy1 = array[i1].pt.y - pt0.y;
dx2 = array[i2].pt.x - pt0.x;
dy2 = array[i2].pt.y - pt0.y;
if( (dx1 | dy1) == 0 || (dx2 | dy2) == 0 )
break;
temp_num = dx1 * dx2 + dy1 * dy2;
temp_num =
(float) (temp_num /
sqrt( ((double)dx1 * dx1 + (double)dy1 * dy1) *
((double)dx2 * dx2 + (double)dy2 * dy2) ));
sk.f = (float) (temp_num + 1.1);
assert( 0 <= sk.f && sk.f <= 2.2 );
if( j < k && sk.i <= s )
break;
s = sk.i;
}
current->s = s;
}
current = current->next;
}
while( current != 0 );
prev_current = &temp;
current = temp.next;
/* Pass 2.
Performs non-maxima suppression */
do
{
int k2 = current->k >> 1;
s = current->s;
i = (int)(current - array);
for( j = 1; j <= k2; j++ )
{
i2 = i - j;
i2 += i2 < 0 ? len : 0;
if( array[i2].s > s )
break;
i2 = i + j;
i2 -= i2 >= len ? len : 0;
if( array[i2].s > s )
break;
}
if( j <= k2 ) /* exclude point */
{
prev_current->next = current->next;
current->s = 0; /* "clear" point */
}
else
prev_current = current;
current = current->next;
}
while( current != 0 );
/* Pass 3.
Removes non-dominant points with 1-length support region */
current = temp.next;
assert( current );
prev_current = &temp;
do
{
if( current->k == 1 )
{
s = current->s;
i = (int)(current - array);
i1 = i - 1;
i1 += i1 < 0 ? len : 0;
i2 = i + 1;
i2 -= i2 >= len ? len : 0;
if( s <= array[i1].s || s <= array[i2].s )
{
prev_current->next = current->next;
current->s = 0;
}
else
prev_current = current;
}
else
prev_current = current;
current = current->next;
}
while( current != 0 );
if( method == CV_CHAIN_APPROX_TC89_KCOS )
goto copy_vect;
/* Pass 4.
Cleans remained couples of points */
assert( temp.next );
if( array[0].s != 0 && array[len - 1].s != 0 ) /* specific case */
{
for( i1 = 1; i1 < len && array[i1].s != 0; i1++ )
{
array[i1 - 1].s = 0;
}
if( i1 == len )
goto copy_vect; /* all points survived */
i1--;
for( i2 = len - 2; i2 > 0 && array[i2].s != 0; i2-- )
{
array[i2].next = 0;
array[i2 + 1].s = 0;
}
i2++;
if( i1 == 0 && i2 == len - 1 ) /* only two points */
{
i1 = (int)(array[0].next - array);
array[len] = array[0]; /* move to the end */
array[len].next = 0;
array[len - 1].next = array + len;
}
temp.next = array + i1;
}
current = temp.next;
first = prev_current = &temp;
count = 1;
/* do last pass */
do
{
if( current->next == 0 || current->next - current != 1 )
{
if( count >= 2 )
{
if( count == 2 )
{
int s1 = prev_current->s;
int s2 = current->s;
if( s1 > s2 || (s1 == s2 && prev_current->k <= current->k) )
/* remove second */
prev_current->next = current->next;
else
/* remove first */
first->next = current;
}
else
first->next->next = current;
}
first = current;
count = 1;
}
else
count++;
prev_current = current;
current = current->next;
}
while( current != 0 );
copy_vect:
// gather points
current = temp.next;
assert( current );
do
{
CV_WRITE_SEQ_ELEM( current->pt, writer );
current = current->next;
}
while( current != 0 );
return cvEndWriteSeq( &writer );
}
/*Applies some approximation algorithm to chain-coded contour(s) and
converts it/them to polygonal representation */
CV_IMPL CvSeq*
cvApproxChains( CvSeq* src_seq,
CvMemStorage* storage,
int method,
double /*parameter*/,
int minimal_perimeter,
int recursive )
{
CvSeq *prev_contour = 0, *parent = 0;
CvSeq *dst_seq = 0;
if( !src_seq || !storage )
CV_Error( CV_StsNullPtr, "" );
if( method > CV_CHAIN_APPROX_TC89_KCOS || method <= 0 || minimal_perimeter < 0 )
CV_Error( CV_StsOutOfRange, "" );
while( src_seq != 0 )
{
int len = src_seq->total;
if( len >= minimal_perimeter )
{
CvSeq *contour = 0;
switch( method )
{
case CV_CHAIN_APPROX_NONE:
case CV_CHAIN_APPROX_SIMPLE:
case CV_CHAIN_APPROX_TC89_L1:
case CV_CHAIN_APPROX_TC89_KCOS:
contour = icvApproximateChainTC89( (CvChain *) src_seq, sizeof( CvContour ), storage, method );
break;
default:
CV_Error( CV_StsOutOfRange, "" );
}
if( contour->total > 0 )
{
cvBoundingRect( contour, 1 );
contour->v_prev = parent;
contour->h_prev = prev_contour;
if( prev_contour )
prev_contour->h_next = contour;
else if( parent )
parent->v_next = contour;
prev_contour = contour;
if( !dst_seq )
dst_seq = prev_contour;
}
else /* if resultant contour has zero length, skip it */
{
len = -1;
}
}
if( !recursive )
break;
if( src_seq->v_next && len >= minimal_perimeter )
{
assert( prev_contour != 0 );
parent = prev_contour;
prev_contour = 0;
src_seq = src_seq->v_next;
}
else
{
while( src_seq->h_next == 0 )
{
src_seq = src_seq->v_prev;
if( src_seq == 0 )
break;
prev_contour = parent;
if( parent )
parent = parent->v_prev;
}
if( src_seq )
src_seq = src_seq->h_next;
}
}
return dst_seq;
}
/****************************************************************************************\
* Polygonal Approximation *
\****************************************************************************************/
/* Ramer-Douglas-Peucker algorithm for polygon simplification */
namespace cv
{
template<typename T> static int
approxPolyDP_( const Point_<T>* src_contour, int count0, Point_<T>* dst_contour,
bool is_closed0, double eps, AutoBuffer<Range>* _stack )
{
#define PUSH_SLICE(slice) \
if( top >= stacksz ) \
{ \
_stack->resize(stacksz*3/2); \
stack = *_stack; \
stacksz = _stack->size(); \
} \
stack[top++] = slice
#define READ_PT(pt, pos) \
pt = src_contour[pos]; \
if( ++pos >= count ) pos = 0
#define READ_DST_PT(pt, pos) \
pt = dst_contour[pos]; \
if( ++pos >= count ) pos = 0
#define WRITE_PT(pt) \
dst_contour[new_count++] = pt
typedef cv::Point_<T> PT;
int init_iters = 3;
Range slice(0, 0), right_slice(0, 0);
PT start_pt((T)-1000000, (T)-1000000), end_pt(0, 0), pt(0,0);
int i = 0, j, pos = 0, wpos, count = count0, new_count=0;
int is_closed = is_closed0;
bool le_eps = false;
size_t top = 0, stacksz = _stack->size();
Range* stack = *_stack;
if( count == 0 )
return 0;
eps *= eps;
if( !is_closed )
{
right_slice.start = count;
end_pt = src_contour[0];
start_pt = src_contour[count-1];
if( start_pt.x != end_pt.x || start_pt.y != end_pt.y )
{
slice.start = 0;
slice.end = count - 1;
PUSH_SLICE(slice);
}
else
{
is_closed = 1;
init_iters = 1;
}
}
if( is_closed )
{
// 1. Find approximately two farthest points of the contour
right_slice.start = 0;
for( i = 0; i < init_iters; i++ )
{
double dist, max_dist = 0;
pos = (pos + right_slice.start) % count;
READ_PT(start_pt, pos);
for( j = 1; j < count; j++ )
{
double dx, dy;
READ_PT(pt, pos);
dx = pt.x - start_pt.x;
dy = pt.y - start_pt.y;
dist = dx * dx + dy * dy;
if( dist > max_dist )
{
max_dist = dist;
right_slice.start = j;
}
}
le_eps = max_dist <= eps;
}
// 2. initialize the stack
if( !le_eps )
{
right_slice.end = slice.start = pos % count;
slice.end = right_slice.start = (right_slice.start + slice.start) % count;
PUSH_SLICE(right_slice);
PUSH_SLICE(slice);
}
else
WRITE_PT(start_pt);
}
// 3. run recursive process
while( top > 0 )
{
slice = stack[--top];
end_pt = src_contour[slice.end];
pos = slice.start;
READ_PT(start_pt, pos);
if( pos != slice.end )
{
double dx, dy, dist, max_dist = 0;
dx = end_pt.x - start_pt.x;
dy = end_pt.y - start_pt.y;
assert( dx != 0 || dy != 0 );
while( pos != slice.end )
{
READ_PT(pt, pos);
dist = fabs((pt.y - start_pt.y) * dx - (pt.x - start_pt.x) * dy);
if( dist > max_dist )
{
max_dist = dist;
right_slice.start = (pos+count-1)%count;
}
}
le_eps = max_dist * max_dist <= eps * (dx * dx + dy * dy);
}
else
{
le_eps = true;
// read starting point
start_pt = src_contour[slice.start];
}
if( le_eps )
{
WRITE_PT(start_pt);
}
else
{
right_slice.end = slice.end;
slice.end = right_slice.start;
PUSH_SLICE(right_slice);
PUSH_SLICE(slice);
}
}
if( !is_closed )
WRITE_PT( src_contour[count-1] );
// last stage: do final clean-up of the approximated contour -
// remove extra points on the [almost] stright lines.
is_closed = is_closed0;
count = new_count;
pos = is_closed ? count - 1 : 0;
READ_DST_PT(start_pt, pos);
wpos = pos;
READ_DST_PT(pt, pos);
for( i = !is_closed; i < count - !is_closed && new_count > 2; i++ )
{
double dx, dy, dist, successive_inner_product;
READ_DST_PT( end_pt, pos );
dx = end_pt.x - start_pt.x;
dy = end_pt.y - start_pt.y;
dist = fabs((pt.x - start_pt.x)*dy - (pt.y - start_pt.y)*dx);
successive_inner_product = (pt.x - start_pt.x) * (end_pt.x - pt.x) +
(pt.y - start_pt.y) * (end_pt.y - pt.y);
if( dist * dist <= 0.5*eps*(dx*dx + dy*dy) && dx != 0 && dy != 0 &&
successive_inner_product >= 0 )
{
new_count--;
dst_contour[wpos] = start_pt = end_pt;
if(++wpos >= count) wpos = 0;
READ_DST_PT(pt, pos);
i++;
continue;
}
dst_contour[wpos] = start_pt = pt;
if(++wpos >= count) wpos = 0;
pt = end_pt;
}
if( !is_closed )
dst_contour[wpos] = pt;
return new_count;
}
}
void cv::approxPolyDP( InputArray _curve, OutputArray _approxCurve,
double epsilon, bool closed )
{
Mat curve = _curve.getMat();
int npoints = curve.checkVector(2), depth = curve.depth();
CV_Assert( npoints >= 0 && (depth == CV_32S || depth == CV_32F));
if( npoints == 0 )
{
_approxCurve.release();
return;
}
AutoBuffer<Point> _buf(npoints);
AutoBuffer<Range> _stack(npoints);
Point* buf = _buf;
int nout = 0;
if( depth == CV_32S )
nout = approxPolyDP_(curve.ptr<Point>(), npoints, buf, closed, epsilon, &_stack);
else if( depth == CV_32F )
nout = approxPolyDP_(curve.ptr<Point2f>(), npoints, (Point2f*)buf, closed, epsilon, &_stack);
else
CV_Error( CV_StsUnsupportedFormat, "" );
Mat(nout, 1, CV_MAKETYPE(depth, 2), buf).copyTo(_approxCurve);
}
CV_IMPL CvSeq*
cvApproxPoly( const void* array, int header_size,
CvMemStorage* storage, int method,
double parameter, int parameter2 )
{
cv::AutoBuffer<cv::Point> _buf;
cv::AutoBuffer<cv::Range> stack(100);
CvSeq* dst_seq = 0;
CvSeq *prev_contour = 0, *parent = 0;
CvContour contour_header;
CvSeq* src_seq = 0;
CvSeqBlock block;
int recursive = 0;
if( CV_IS_SEQ( array ))
{
src_seq = (CvSeq*)array;
if( !CV_IS_SEQ_POLYLINE( src_seq ))
CV_Error( CV_StsBadArg, "Unsupported sequence type" );
recursive = parameter2;
if( !storage )
storage = src_seq->storage;
}
else
{
src_seq = cvPointSeqFromMat(
CV_SEQ_KIND_CURVE | (parameter2 ? CV_SEQ_FLAG_CLOSED : 0),
array, &contour_header, &block );
}
if( !storage )
CV_Error( CV_StsNullPtr, "NULL storage pointer " );
if( header_size < 0 )
CV_Error( CV_StsOutOfRange, "header_size is negative. "
"Pass 0 to make the destination header_size == input header_size" );
if( header_size == 0 )
header_size = src_seq->header_size;
if( !CV_IS_SEQ_POLYLINE( src_seq ))
{
if( CV_IS_SEQ_CHAIN( src_seq ))
{
CV_Error( CV_StsBadArg, "Input curves are not polygonal. "
"Use cvApproxChains first" );
}
else
{
CV_Error( CV_StsBadArg, "Input curves have uknown type" );
}
}
if( header_size == 0 )
header_size = src_seq->header_size;
if( header_size < (int)sizeof(CvContour) )
CV_Error( CV_StsBadSize, "New header size must be non-less than sizeof(CvContour)" );
if( method != CV_POLY_APPROX_DP )
CV_Error( CV_StsOutOfRange, "Unknown approximation method" );
while( src_seq != 0 )
{
CvSeq *contour = 0;
switch (method)
{
case CV_POLY_APPROX_DP:
if( parameter < 0 )
CV_Error( CV_StsOutOfRange, "Accuracy must be non-negative" );
CV_Assert( CV_SEQ_ELTYPE(src_seq) == CV_32SC2 ||
CV_SEQ_ELTYPE(src_seq) == CV_32FC2 );
{
int npoints = src_seq->total, nout = 0;
_buf.allocate(npoints*2);
cv::Point *src = _buf, *dst = src + npoints;
bool closed = CV_IS_SEQ_CLOSED(src_seq);
if( src_seq->first->next == src_seq->first )
src = (cv::Point*)src_seq->first->data;
else
cvCvtSeqToArray(src_seq, src);
if( CV_SEQ_ELTYPE(src_seq) == CV_32SC2 )
nout = cv::approxPolyDP_(src, npoints, dst, closed, parameter, &stack);
else if( CV_SEQ_ELTYPE(src_seq) == CV_32FC2 )
nout = cv::approxPolyDP_((cv::Point2f*)src, npoints,
(cv::Point2f*)dst, closed, parameter, &stack);
else
CV_Error( CV_StsUnsupportedFormat, "" );
contour = cvCreateSeq( src_seq->flags, header_size,
src_seq->elem_size, storage );
cvSeqPushMulti(contour, dst, nout);
}
break;
default:
CV_Error( CV_StsBadArg, "Invalid approximation method" );
}
assert( contour );
if( header_size >= (int)sizeof(CvContour))
cvBoundingRect( contour, 1 );
contour->v_prev = parent;
contour->h_prev = prev_contour;
if( prev_contour )
prev_contour->h_next = contour;
else if( parent )
parent->v_next = contour;
prev_contour = contour;
if( !dst_seq )
dst_seq = prev_contour;
if( !recursive )
break;
if( src_seq->v_next )
{
assert( prev_contour != 0 );
parent = prev_contour;
prev_contour = 0;
src_seq = src_seq->v_next;
}
else
{
while( src_seq->h_next == 0 )
{
src_seq = src_seq->v_prev;
if( src_seq == 0 )
break;
prev_contour = parent;
if( parent )
parent = parent->v_prev;
}
if( src_seq )
src_seq = src_seq->h_next;
}
}
return dst_seq;
}
/* End of file. */