bool ReaderImpl::ReadPointAt(std::size_t n, LASPoint& point, const LASHeader& header)
{
// Read point data record format 0
// TODO: Replace with compile-time assert
double t=0;
detail::PointRecord record;
assert(LASHeader::ePointSize0 == sizeof(record));
if (m_size <= n)
return false;
std::streamsize pos = (static_cast<std::streamsize>(n) * m_recordlength) + m_offset;
m_ifs.clear();
m_ifs.seekg(pos, std::ios::beg);
detail::read_n(record, m_ifs, sizeof(record));
Reader::FillPoint(record, point);
point.SetCoordinates(header, point.GetX(), point.GetY(), point.GetZ());
if (header.GetDataFormatId() == LASHeader::ePointFormat1) {
detail::read_n(t, m_ifs, sizeof(double));
point.SetTime(t);
}
return true;
}
void WriterImpl::WriteVLR(LASHeader const& header)
{
m_ofs.seekp(header.GetHeaderSize(), std::ios::beg);
for (uint32_t i = 0; i < header.GetRecordsCount(); ++i)
{
LASVLR vlr = header.GetVLR(i);
detail::write_n(m_ofs, vlr.GetReserved(), sizeof(uint16_t));
detail::write_n(m_ofs, vlr.GetUserId(true).c_str(), 16);
detail::write_n(m_ofs, vlr.GetRecordId(), sizeof(uint16_t));
detail::write_n(m_ofs, vlr.GetRecordLength(), sizeof(uint16_t));
detail::write_n(m_ofs, vlr.GetDescription(true).c_str(), 32);
std::vector<uint8_t> const& data = vlr.GetData();
std::streamsize const size = static_cast<std::streamsize>(data.size());
detail::write_n(m_ofs, data.front(), size);
}
}
void WriterImpl::UpdateHeader(LASHeader const& header)
{
if (m_pointCount != header.GetPointRecordsCount())
{
// Skip to first byte of number of point records data member
std::streamsize const dataPos = 107;
m_ofs.seekp(dataPos, std::ios::beg);
detail::write_n(m_ofs, m_pointCount , sizeof(m_pointCount));
}
}
bool ReaderImpl::ReadNextPoint(LASPoint& point, const LASHeader& header)
{
// Read point data record format 0
// TODO: Replace with compile-time assert
detail::PointRecord record;
double t=0;
assert(LASHeader::ePointSize0 == sizeof(record));
if (0 == m_current)
{
m_ifs.clear();
m_ifs.seekg(m_offset, std::ios::beg);
}
if (m_current < m_size)
{
try
{
detail::read_n(record, m_ifs, sizeof(PointRecord));
++m_current;
}
catch (std::out_of_range const& e) // we reached the end of the file
{
std::cerr << e.what() << std::endl;
return false;
}
Reader::FillPoint(record, point);
point.SetCoordinates(header, point.GetX(), point.GetY(), point.GetZ());
if (header.GetDataFormatId() == LASHeader::ePointFormat1) {
detail::read_n(t, m_ifs, sizeof(double));
point.SetTime(t);
}
return true;
}
return false;
}
void WriterImpl::WriteHeader(LASHeader& header)
{
uint8_t n1 = 0;
uint16_t n2 = 0;
uint32_t n4 = 0;
// Rewrite the georeference VLR entries if they exist
header.SetGeoreference();
// Seek to the beginning
m_ofs.seekp(0, std::ios::beg);
std::ios::pos_type beginning = m_ofs.tellp();
// Seek to the end
m_ofs.seekp(0, std::ios::end);
std::ios::pos_type end = m_ofs.tellp();
// Figure out how many points we already have. Each point record
// should be 20 bytes long, and header.GetDataOffset tells
// us the location to start counting points from.
// This test should only be true if we were opened in both
// std::ios::in *and* std::ios::out, otherwise it should return false
// and we won't adjust the point count.
if ((beginning != end) && ((uint32_t)end != 0)) {
m_pointCount = ((uint32_t) end - header.GetDataOffset())/header.GetDataRecordLength();
// Position to the beginning of the file to start writing the header
m_ofs.seekp(0, std::ios::beg);
}
// 1. File Signature
std::string const filesig(header.GetFileSignature());
assert(filesig.size() == 4);
detail::write_n(m_ofs, filesig, 4);
// 2. Reserved
n4 = header.GetReserved();
detail::write_n(m_ofs, n4, sizeof(n4));
// 3-6. GUID data
uint32_t d1 = 0;
uint16_t d2 = 0;
uint16_t d3 = 0;
uint8_t d4[8] = { 0 };
liblas::guid g = header.GetProjectId();
g.output_data(d1, d2, d3, d4);
detail::write_n(m_ofs, d1, sizeof(d1));
detail::write_n(m_ofs, d2, sizeof(d2));
detail::write_n(m_ofs, d3, sizeof(d3));
detail::write_n(m_ofs, d4, sizeof(d4));
// 7. Version major
n1 = header.GetVersionMajor();
assert(1 == n1);
detail::write_n(m_ofs, n1, sizeof(n1));
// 8. Version minor
n1 = header.GetVersionMinor();
assert(0 == n1);
detail::write_n(m_ofs, n1, sizeof(n1));
// 9. System ID
std::string sysid(header.GetSystemId(true));
assert(sysid.size() == 32);
detail::write_n(m_ofs, sysid, 32);
// 10. Generating Software ID
std::string softid(header.GetSoftwareId(true));
assert(softid.size() == 32);
detail::write_n(m_ofs, softid, 32);
// 11. Flight Date Julian
n2 = header.GetCreationDOY();
detail::write_n(m_ofs, n2, sizeof(n2));
// 12. Year
n2 = header.GetCreationYear();
detail::write_n(m_ofs, n2, sizeof(n2));
// 13. Header Size
n2 = header.GetHeaderSize();
assert(227 <= n2);
detail::write_n(m_ofs, n2, sizeof(n2));
// 14. Offset to data
n4 = header.GetDataOffset();
detail::write_n(m_ofs, n4, sizeof(n4));
// 15. Number of variable length records
// TODO: This value must be updated after new variable length record is added.
n4 = header.GetRecordsCount();
detail::write_n(m_ofs, n4, sizeof(n4));
// 16. Point Data Format ID
n1 = static_cast<uint8_t>(header.GetDataFormatId());
detail::write_n(m_ofs, n1, sizeof(n1));
// 17. Point Data Record Length
n2 = header.GetDataRecordLength();
detail::write_n(m_ofs, n2, sizeof(n2));
// 18. Number of point records
// This value is updated if necessary, see UpdateHeader function.
n4 = header.GetPointRecordsCount();
detail::write_n(m_ofs, n4, sizeof(n4));
// 19. Number of points by return
std::vector<uint32_t>::size_type const srbyr = 5;
std::vector<uint32_t> const& vpbr = header.GetPointRecordsByReturnCount();
assert(vpbr.size() <= srbyr);
uint32_t pbr[srbyr] = { 0 };
std::copy(vpbr.begin(), vpbr.end(), pbr);
detail::write_n(m_ofs, pbr, sizeof(pbr));
// 20-22. Scale factors
detail::write_n(m_ofs, header.GetScaleX(), sizeof(double));
detail::write_n(m_ofs, header.GetScaleY(), sizeof(double));
detail::write_n(m_ofs, header.GetScaleZ(), sizeof(double));
// 23-25. Offsets
detail::write_n(m_ofs, header.GetOffsetX(), sizeof(double));
detail::write_n(m_ofs, header.GetOffsetY(), sizeof(double));
detail::write_n(m_ofs, header.GetOffsetZ(), sizeof(double));
// 26-27. Max/Min X
detail::write_n(m_ofs, header.GetMaxX(), sizeof(double));
detail::write_n(m_ofs, header.GetMinX(), sizeof(double));
// 28-29. Max/Min Y
detail::write_n(m_ofs, header.GetMaxY(), sizeof(double));
detail::write_n(m_ofs, header.GetMinY(), sizeof(double));
// 30-31. Max/Min Z
detail::write_n(m_ofs, header.GetMaxZ(), sizeof(double));
detail::write_n(m_ofs, header.GetMinZ(), sizeof(double));
WriteVLR(header);
uint8_t const sgn1 = 0xCC;
uint8_t const sgn2 = 0xDD;
detail::write_n(m_ofs, sgn1, sizeof(uint8_t));
detail::write_n(m_ofs, sgn2, sizeof(uint8_t));
// If we already have points, we're going to put it at the end of the file.
// If we don't have any points, we're going to leave it where it is.
if (m_pointCount != 0)
m_ofs.seekp(0, std::ios::end);
}
bool ReaderImpl::ReadHeader(LASHeader& header)
{
using detail::read_n;
// Helper variables
uint8_t n1 = 0;
uint16_t n2 = 0;
uint32_t n4 = 0;
double x1 = 0;
double y1 = 0;
double z1 = 0;
double x2 = 0;
double y2 = 0;
double z2 = 0;
std::string buf;
std::string fsig;
m_ifs.seekg(0);
// 1. File Signature
read_n(fsig, m_ifs, 4);
header.SetFileSignature(fsig);
// 2. Reserved
// This data must always contain Zeros.
read_n(n4, m_ifs, sizeof(n4));
// 3-6. GUID data
uint32_t d1 = 0;
uint16_t d2 = 0;
uint16_t d3 = 0;
uint8_t d4[8] = { 0 };
read_n(d1, m_ifs, sizeof(d1));
read_n(d2, m_ifs, sizeof(d2));
read_n(d3, m_ifs, sizeof(d3));
read_n(d4, m_ifs, sizeof(d4));
liblas::guid g(d1, d2, d3, d4);
header.SetProjectId(g);
// 7. Version major
read_n(n1, m_ifs, sizeof(n1));
header.SetVersionMajor(n1);
// 8. Version minor
read_n(n1, m_ifs, sizeof(n1));
header.SetVersionMinor(n1);
// 9. System ID
read_n(buf, m_ifs, 32);
header.SetSystemId(buf);
// 10. Generating Software ID
read_n(buf, m_ifs, 32);
header.SetSoftwareId(buf);
// 11. Flight Date Julian
read_n(n2, m_ifs, sizeof(n2));
header.SetCreationDOY(n2);
// 12. Year
read_n(n2, m_ifs, sizeof(n2));
header.SetCreationYear(n2);
// 13. Header Size
// NOTE: Size of the stanard header block must always be 227 bytes
read_n(n2, m_ifs, sizeof(n2));
// 14. Offset to data
read_n(n4, m_ifs, sizeof(n4));
if (n4 < header.GetHeaderSize())
{
// TODO: Move this test to LASHeader::Validate()
throw std::domain_error("offset to point data smaller than header size");
}
header.SetDataOffset(n4);
// 15. Number of variable length records
read_n(n4, m_ifs, sizeof(n4));
header.SetRecordsCount(n4);
// 16. Point Data Format ID
read_n(n1, m_ifs, sizeof(n1));
if (n1 == LASHeader::ePointFormat0) {
header.SetDataFormatId(LASHeader::ePointFormat0);
}
else if (n1 == LASHeader::ePointFormat1) {
header.SetDataFormatId(LASHeader::ePointFormat1);
}
else if (n1 == LASHeader::ePointFormat2) {
header.SetDataFormatId(LASHeader::ePointFormat2);
}
else if (n1 == LASHeader::ePointFormat3) {
header.SetDataFormatId(LASHeader::ePointFormat3);
}
else {
throw std::domain_error("invalid point data format");
}
// 17. Point Data Record Length
// NOTE: No need to set record length because it's
// determined on basis of point data format.
read_n(n2, m_ifs, sizeof(n2));
// 18. Number of point records
read_n(n4, m_ifs, sizeof(n4));
header.SetPointRecordsCount(n4);
// 19. Number of points by return
std::vector<uint32_t>::size_type const srbyr = 5;
uint32_t rbyr[srbyr] = { 0 };
read_n(rbyr, m_ifs, sizeof(rbyr));
for (std::size_t i = 0; i < srbyr; ++i)
{
header.SetPointRecordsByReturnCount(i, rbyr[i]);
}
// 20-22. Scale factors
read_n(x1, m_ifs, sizeof(x1));
read_n(y1, m_ifs, sizeof(y1));
read_n(z1, m_ifs, sizeof(z1));
header.SetScale(x1, y1, z1);
// 23-25. Offsets
read_n(x1, m_ifs, sizeof(x1));
read_n(y1, m_ifs, sizeof(y1));
read_n(z1, m_ifs, sizeof(z1));
header.SetOffset(x1, y1, z1);
// 26-27. Max/Min X
read_n(x1, m_ifs, sizeof(x1));
read_n(x2, m_ifs, sizeof(x2));
// 28-29. Max/Min Y
read_n(y1, m_ifs, sizeof(y1));
read_n(y2, m_ifs, sizeof(y2));
// 30-31. Max/Min Z
read_n(z1, m_ifs, sizeof(z1));
read_n(z2, m_ifs, sizeof(z2));
header.SetMax(x1, y1, z1);
header.SetMin(x2, y2, z2);
Reset(header);
return true;
}