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Preserve original LAS/LAZ intensity field through raycloud pipeline #18

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Merged
tim-devereux merged 1 commit into from
May 19, 2026
Merged

Preserve original LAS/LAZ intensity field through raycloud pipeline #18

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2 changes: 1 addition & 1 deletion raylib/raycloud.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -73,7 +73,7 @@ bool Cloud::loadLas(const std::string &file, int min_num_rays)
if (!pass.empty())
{
passthrough = std::move(pass);
extra_bytes_size = 8 + orig_extra;
extra_bytes_size = 10 + orig_extra;
extra_bytes_vlr = std::move(orig_vlr);
}
if ((int)ends.size() < min_num_rays)
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2 changes: 1 addition & 1 deletion raylib/raydecimation.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -22,7 +22,7 @@ static bool beginWriter(CloudWriter &writer, const std::string &out_file,
uint16_t orig_extra = 0;
if (ext == "las" || ext == "laz")
readLasExtraBytesVlr(in_file, orig_extra, extra_bytes_vlr_out);
pass_stride_out = static_cast<uint16_t>(8 + orig_extra);
pass_stride_out = static_cast<uint16_t>(10 + orig_extra);
return writer.begin(out_file, extra_bytes_vlr_out);
}

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31 changes: 22 additions & 9 deletions raylib/raylaz.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -192,13 +192,14 @@ bool readLas(const std::string &file_name,
starts.push_back(position);
}

// Pack 8 bytes of LAS 1.4 extended fields per point into passthrough.
// Pack 10 bytes of LAS fields per point into passthrough, followed by sensor extras.
// Layout: [0] ext_return[0:3]|ext_num_returns[4:7]
// [1] class_flags[0:3]|scanner_chan[4:5]|scan_dir[6]|edge[7]
// [2] extended_classification
// [3] user_data
// [4-5] extended_scan_angle (int16 LE, 0.006 deg units)
// [6-7] point_source_ID (uint16 LE)
// [8-9] original intensity (uint16 LE)
if (passthrough_out)
{
uint8_t b0, b1, b2;
Expand Down Expand Up @@ -236,6 +237,9 @@ bool readLas(const std::string &file_name,
passthrough_out->push_back(static_cast<uint8_t>(static_cast<uint16_t>(ext_angle) >> 8));
passthrough_out->push_back(static_cast<uint8_t>(point->point_source_ID & 0xFFu));
passthrough_out->push_back(static_cast<uint8_t>(point->point_source_ID >> 8));
// Original intensity (uint16 LE) — preserved so the output keeps the sensor value.
passthrough_out->push_back(static_cast<uint8_t>(point->intensity & 0xFFu));
passthrough_out->push_back(static_cast<uint8_t>(point->intensity >> 8));
// Append original sensor extra bytes (after skipping our raycloud-owned attributes).
if (local_orig_extra > 0 && point->num_extra_bytes >= local_skip_size + local_orig_extra)
passthrough_out->insert(passthrough_out->end(),
Expand All @@ -259,13 +263,20 @@ bool readLas(const std::string &file_name,
uint8_t intensity;
if (is_raycloud)
{
// Alpha is stored directly in the intensity field (0-255).
intensity = static_cast<uint8_t>(point->intensity);
// Alpha is stored in extra_bytes at position 12 (or 16 with tree_id).
// Prefer extra_bytes so the intensity field is free to carry the original sensor value.
const uint16_t alpha_pos = has_tree_id_attr ? 16u : 12u;
intensity = (point->num_extra_bytes > alpha_pos)
? point->extra_bytes[alpha_pos]
: static_cast<uint8_t>(point->intensity); // fallback for old files
}
else
{
const double normalised = (max_intensity > 0) ? (255.0 * point->intensity) / max_intensity : 255.0;
intensity = static_cast<uint8_t>(std::min(normalised, 255.0));
// Ensure any non-zero raw intensity maps to at least alpha=1 (bounded ray).
if (intensity == 0 && point->intensity > 0)
intensity = 1;
}
if (intensity > 0)
num_bounded++;
Expand Down Expand Up @@ -628,7 +639,7 @@ LasRayCloudWriter::LasRayCloudWriter(const std::string &file_name, bool with_tre
, points_written_(0)
, with_tree_id_(with_tree_id)
, orig_extra_size_(0)
, passthrough_stride_(8)
, passthrough_stride_(10)
, writer_handle_(nullptr)
, point_(nullptr)
{
Expand Down Expand Up @@ -692,7 +703,7 @@ LasRayCloudWriter::LasRayCloudWriter(const std::string &file_name, bool with_tre
laszip_add_attribute(writer_handle_, static_cast<laszip_U32>(dtype - 1), name, desc, scale_v, offset_v);
orig_extra_size_ += kTypeSize[dtype];
}
passthrough_stride_ = static_cast<uint16_t>(8 + orig_extra_size_);
passthrough_stride_ = static_cast<uint16_t>(10 + orig_extra_size_);

// LAS 1.4 format 7 base = 36 bytes.
const laszip_U16 record_size =
Expand Down Expand Up @@ -803,8 +814,8 @@ bool LasRayCloudWriter::writeChunk(const std::vector<Eigen::Vector3d> &starts,
point_->rgb[0] = static_cast<laszip_U16>(colours[i].red) * 257u;
point_->rgb[1] = static_cast<laszip_U16>(colours[i].green) * 257u;
point_->rgb[2] = static_cast<laszip_U16>(colours[i].blue) * 257u;
// Restore LAS 1.4 extended fields from passthrough if available.
// First 8 bytes: standard LAS fields. Bytes [8..] are original sensor extra bytes.
// Restore LAS fields from passthrough if available.
// Layout: [0-7] standard LAS fields, [8-9] original intensity (uint16 LE), [10..] sensor extras.
if (passthrough.size() >= (i + 1) * passthrough_stride_)
{
const uint8_t *p = passthrough.data() + i * passthrough_stride_;
Expand All @@ -820,11 +831,13 @@ bool LasRayCloudWriter::writeChunk(const std::vector<Eigen::Vector3d> &starts,
std::memcpy(&ext_angle, p + 4, 2);
point_->extended_scan_angle = ext_angle;
point_->point_source_ID = static_cast<laszip_U16>(p[6]) | (static_cast<laszip_U16>(p[7]) << 8);
// Original sensor extra bytes follow the standard 8 bytes.
// Restore original intensity from p[8..9], overriding the alpha default set above.
std::memcpy(&point_->intensity, p + 8, 2);
// Original sensor extra bytes at p[10..].
if (orig_extra_size_ > 0)
{
const uint16_t orig_start = static_cast<uint16_t>(with_tree_id_ ? 17 : 13);
std::memcpy(point_->extra_bytes + orig_start, p + 8, orig_extra_size_);
std::memcpy(point_->extra_bytes + orig_start, p + 10, orig_extra_size_);
}
}
// Store start - end as three float32 extra bytes so starts can be reconstructed.
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2 changes: 1 addition & 1 deletion raylib/raylaz.h
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Original file line number Diff line number Diff line change
Expand Up @@ -105,7 +105,7 @@ class RAYLIB_EXPORT LasRayCloudWriter
uint64_t points_written_ = 0;
bool with_tree_id_ = false;
uint16_t orig_extra_size_ = 0; ///< per-point original sensor extra bytes
uint16_t passthrough_stride_ = 8; ///< 8 + orig_extra_size_
uint16_t passthrough_stride_ = 10; ///< 10 + orig_extra_size_
#if RAYLIB_WITH_LAS
laszip_POINTER writer_handle_;
laszip_point_struct *point_;
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