//:
// Assumes given a Lookup table of integer squares.
// Also assumes the image \a im already has infinity in all non-zero points.
bool SaitoSquaredDistanceTransform::SDT_2D(Grid3D<GridElement>& grid, size_t sliceIndex, const std::vector<GridElement>& sq)
{
const Tuple3ui& gridSize = grid.size();
size_t r = gridSize.y;
size_t c = gridSize.x;
size_t voxelCount = r*c;
GridElement* sliceData = grid.data() + sliceIndex * voxelCount;
// 1st step: vertical row-wise EDT
{
if (!EDT_1D(sliceData, r, c))
{
return false;
}
}
// 2nd step: horizontal scan
{
std::vector<GridElement> colData;
try
{
colData.resize(r);
}
catch (const std::bad_alloc&)
{
//not enough memory
return false;
}
//for each column
for (size_t i = 0; i < c; ++i)
{
//fill buffer with column values
{
GridElement* pt = sliceData + i;
for (size_t j = 0; j < r; ++j, pt += c)
colData[j] = *pt;
}
//forward scan
GridElement* pt = sliceData + i + c;
{
GridElement a = 0;
GridElement buffer = colData[0];
for (size_t j = 1; j < r; ++j, pt += c)
{
size_t rowIndex = j;
if (a != 0)
--a;
if (colData[rowIndex] > buffer + 1)
{
GridElement b = (colData[rowIndex] - buffer - 1) / 2;
if (rowIndex + b + 1 > r)
b = static_cast<GridElement>(r - 1 - rowIndex);
GridElement* npt = pt + a*c;
for (GridElement l = a; l <= b; ++l)
{
GridElement m = buffer + sq[l + 1];
if (colData[rowIndex + l] <= m)
{
//proceed to next column
break;
}
if (m < *npt)
*npt = m;
npt += c;
}
a = b;
}
else
{
a = 0;
}
buffer = colData[rowIndex];
}
}
//backward scan
pt -= 2 * c;
{
GridElement a = 0;
GridElement buffer = colData[r - 1];
for (size_t j = 1; j < r; ++j, pt -= c)
{
size_t rowIndex = r - j - 1;
if (a != 0)
--a;
if (colData[rowIndex] > buffer + 1)
{
GridElement b = (colData[rowIndex] - buffer - 1) / 2;
if (rowIndex < b)
b = static_cast<GridElement>(rowIndex);
GridElement* npt = pt - a*c;
for (GridElement l = a; l <= b; ++l)
{
GridElement m = buffer + sq[l + 1];
if (colData[rowIndex - l] <= m)
{
//proceed to next column
break;
}
if (m < *npt)
*npt = m;
npt -= c;
}
a = b;
}
else
{
a = 0;
}
buffer = colData[rowIndex];
}
}
}
}
return true;
}
bool SaitoSquaredDistanceTransform::SDT_3D(Grid3D<GridElement>& grid, GenericProgressCallback* progressCb/*=0*/)
{
const Tuple3ui& gridSize = grid.size();
size_t r = gridSize.y;
size_t c = gridSize.x;
size_t p = gridSize.z;
size_t voxelCount = r*c*p;
size_t diag = static_cast<size_t>(ceil(sqrt(static_cast<double>(r*r + c*c + p*p))) - 1);
size_t nsqr = 2 * (diag + 1);
std::vector<GridElement> sq;
try
{
sq.resize(nsqr);
}
catch (const std::bad_alloc&)
{
//not enough memory
return false;
}
for (size_t i = 0; i < nsqr; ++i)
{
sq[i] = static_cast<GridElement>(i*i);
}
const GridElement maxDistance = std::numeric_limits<GridElement>::max() - static_cast<GridElement>(r*r - c*c - p*p) - 1;
NormalizedProgress normProgress(progressCb, static_cast<unsigned>(p + r));
if (progressCb)
{
progressCb->setMethodTitle("Saito Distance Transform");
char buffer[256];
sprintf(buffer, "Box: [%u x %u x %u]", gridSize.x, gridSize.y, gridSize.z);
progressCb->setInfo(buffer);
progressCb->reset();
progressCb->start();
}
GridElement* data = grid.data();
{
for (size_t i = 0; i < voxelCount; ++i)
{
//DGM: warning we must invert the input image here!
if (data[i] == 0)
data[i] = maxDistance;
else
data[i] = 0;
}
}
// 2D EDT for each slice
for (size_t k = 0; k < p; ++k)
{
if (!SDT_2D(grid, k, sq))
{
return false;
}
if (progressCb && !normProgress.oneStep())
{
//process cancelled by user
return false;
}
}
// Now, for each pixel, compute final distance by searching along Z direction
size_t rc = r*c;
std::vector<GridElement> colData;
try
{
colData.resize(p);
}
catch (const std::bad_alloc&)
{
//not enough memory
return false;
}
for (size_t j = 0; j < r; ++j, data += c)
{
for (size_t i = 0; i < c; ++i)
{
GridElement* pt = data + i;
for (size_t k = 0; k < p; ++k, pt += rc)
colData[k] = *pt;
pt = data + i + rc;
GridElement a = 0;
GridElement buffer = colData[0];
for (size_t k = 1; k < p; ++k, pt += rc)
{
if (a != 0)
--a;
if (colData[k] > buffer + 1)
{
GridElement b = (colData[k] - buffer - 1) / 2;
if (k + b + 1 > p)
b = static_cast<GridElement>(p - 1 - k);
GridElement* npt = pt + a*rc;
for (GridElement l = a; l <= b; ++l)
{
GridElement m = buffer + sq[l + 1];
if (colData[k + l] <= m)
break; // go to next plane k
if (m < *npt)
*npt = m;
npt += rc;
}
a = b;
}
else
{
a = 0;
}
buffer = colData[k];
}
a = 0;
pt -= 2 * rc;
buffer = colData[p - 1];
for (size_t k = p - 2; k != static_cast<size_t>(-1); --k, pt -= rc)
{
if (a != 0)
--a;
if (colData[k] > buffer + 1)
{
GridElement b = (colData[k] - buffer - 1) / 2;
if (k < b)
b = static_cast<GridElement>(k);
GridElement* npt = pt - a*rc;
for (GridElement l = a; l <= b; ++l)
{
GridElement m = buffer + sq[l + 1];
if (colData[k - l] <= m)
break; // go to next column k
if (m < *npt)
*npt = m;
npt -= rc;
}
a = b;
}
else
{
a = 0;
}
buffer = colData[k];
}
}
if (progressCb && !normProgress.oneStep())
{
//process cancelled by user
return false;
}
}
return true;
}
