mirror of
https://gitlab.com/freepascal.org/lazarus/lazarus.git
synced 2025-05-10 22:02:39 +02:00
268 lines
9.6 KiB
ObjectPascal
268 lines
9.6 KiB
ObjectPascal
{
|
|
lasvectorialreader.pas
|
|
|
|
Reads geospatial data encoded in the ASPRS LASer (LAS) file format version 1.3
|
|
|
|
LAS file format specification obtained from:
|
|
|
|
http://www.asprs.org/a/society/committees/standards/lidar_exchange_format.html
|
|
LAS 1.3 r11
|
|
|
|
All data is in little-endian format.
|
|
|
|
AUTHORS: Felipe Monteiro de Carvalho
|
|
|
|
License: The same modified LGPL as the Free Pascal RTL
|
|
See the file COPYING.modifiedLGPL for more details
|
|
}
|
|
unit lasvectorialreader;
|
|
|
|
{$ifdef fpc}
|
|
{$mode delphi}
|
|
{$endif}
|
|
|
|
{$define FPVECTORIALDEBUG_LAS}
|
|
|
|
interface
|
|
|
|
uses
|
|
Classes, SysUtils,
|
|
//avisozlib,
|
|
fpvectorial;
|
|
|
|
type
|
|
// LAS data types introduced in LAS 1.0
|
|
laschar = AnsiChar; // or ShortInt
|
|
lasuchar = Byte;
|
|
lasshort = Smallint;
|
|
lasushort = Word;
|
|
laslong = Integer;
|
|
lasulong = Cardinal;
|
|
lasdouble = double;
|
|
//
|
|
laslonglong = Int64;
|
|
lasulonglong = QWord;
|
|
|
|
// PUBLIC HEADER BLOCK version 1.0
|
|
TLASPublicHeaderBlock_1_0 = packed record
|
|
FileSignatureLASF: array[0..3] of laschar;
|
|
FileSourceID: lasushort; // Reserved in LAS 1.0
|
|
GlobalEncoding: lasushort; // Reserved in LAS 1.0
|
|
ProjectIDGUIDdata1: lasulong; // Optional
|
|
ProjectIDGUIDdata2: lasushort; // Optional
|
|
ProjectIDGUIDdata3: lasushort; // Optional
|
|
ProjectIDGUIDdata4: array[0..7] of lasuchar;// Optional
|
|
VersionMajor: lasuchar;
|
|
VersionMinor: lasuchar;
|
|
SystemIdentifier: array[0..31] of laschar;
|
|
GeneratingSoftware: array[0..31] of laschar;
|
|
FileCreationDayofYear: lasushort; // Name in LAS 1.0 -> FlightDateJulian, but same meaning
|
|
FileCreationYear: lasushort; // Name in LAS 1.0 -> Year, but same meaning
|
|
HeaderSize: lasushort; // Name in LAS 1.0 -> OffsetToData
|
|
OffsetToPointData: lasulong;
|
|
NumberofVariableLengthRecords: lasulong;
|
|
PointDataFormatID: lasuchar; // (0-99 for spec)
|
|
PointDataRecordLength: lasushort;
|
|
Numberofpointrecords: lasulong;
|
|
Numberofpointsbyreturn: array[0..4] of lasulong;
|
|
Xscalefactor: lasdouble;
|
|
Yscalefactor: lasdouble;
|
|
Zscalefactor: lasdouble;
|
|
|
|
Xoffset: lasdouble;
|
|
Yoffset: lasdouble;
|
|
Zoffset: lasdouble;
|
|
MaxX: lasdouble;
|
|
MinX: lasdouble;
|
|
MaxY: lasdouble;
|
|
MinY: lasdouble;
|
|
MaxZ: lasdouble;
|
|
MinZ: lasdouble;
|
|
end;
|
|
|
|
// PUBLIC HEADER BLOCK Extension in Version 1.3
|
|
TLASPublicHeaderBlock_1_3_Extension = packed record
|
|
StartofWaveformDataPacket: lasulonglong;
|
|
end;
|
|
|
|
TLASVariableLengthRecord = packed record
|
|
RecordSignatureAABB: lasushort;
|
|
UserID: array[0..15] of laschar;
|
|
RecordID: lasushort;
|
|
RecordLengthAfterHeader: lasushort;
|
|
Description: array[0..31] of laschar;
|
|
end;
|
|
|
|
TLASPointDataRecordFormat0 = packed record
|
|
X: laslong;
|
|
Y: laslong;
|
|
Z: laslong;
|
|
Intensity: lasushort;
|
|
Flags: Byte;
|
|
Classification: lasuchar;
|
|
ScanAngleRank: lasuchar; // (-90 to +90) - is the left side
|
|
FileMarker: lasuchar;
|
|
UserBitField: lasushort;
|
|
end;
|
|
|
|
TLASPointDataRecordFormat1 = packed record
|
|
X: laslong;
|
|
Y: laslong;
|
|
Z: laslong;
|
|
Intensity: lasushort;
|
|
Flags: Byte;
|
|
Classification: lasuchar;
|
|
ScanAngleRank: lasuchar; // (-90 to +90) - is the left side
|
|
FileMarker: lasuchar;
|
|
UserBitField: lasushort;
|
|
GPSTime: lasdouble;
|
|
end;
|
|
|
|
{ TvLASVectorialReader }
|
|
|
|
TvLASVectorialReader = class(TvCustomVectorialReader)
|
|
private
|
|
// Stream position information
|
|
InitialPos, PositionAfterPublicHeader: Int64;
|
|
{$ifdef FPVECTORIALDEBUG_LAS}
|
|
procedure DebugOutPublicHeaderBlock();
|
|
{$endif}
|
|
procedure ReadVariableLengthRecords(AStream: TStream);
|
|
public
|
|
// Public Header
|
|
PublicHeaderBlock_1_0: TLASPublicHeaderBlock_1_0;
|
|
PublicHeaderBlock_1_3_Extension: TLASPublicHeaderBlock_1_3_Extension;
|
|
// Variable Length Records
|
|
VariableLengthRecords: array of TLASVariableLengthRecord;
|
|
// Point Data
|
|
PointsFormat0: array of TLASPointDataRecordFormat0;
|
|
PointsFormat1: array of TLASPointDataRecordFormat1;
|
|
{ General reading methods }
|
|
procedure ReadFromStream(AStream: TStream; AData: TvVectorialDocument); override;
|
|
end;
|
|
|
|
implementation
|
|
|
|
{$ifdef FPVECTORIALDEBUG_LAS}
|
|
procedure TvLASVectorialReader.DebugOutPublicHeaderBlock;
|
|
begin
|
|
WriteLn(Format('FileSignatureLASF = %s = %x %x %x %x',
|
|
[string(PublicHeaderBlock_1_0.FileSignatureLASF),
|
|
Ord(PublicHeaderBlock_1_0.FileSignatureLASF[0]),
|
|
Ord(PublicHeaderBlock_1_0.FileSignatureLASF[1]),
|
|
Ord(PublicHeaderBlock_1_0.FileSignatureLASF[2]),
|
|
Ord(PublicHeaderBlock_1_0.FileSignatureLASF[3])]));
|
|
WriteLn(Format('FileSourceID = $%x', [PublicHeaderBlock_1_0.FileSourceID]));
|
|
WriteLn(Format('GlobalEncoding = $%x', [PublicHeaderBlock_1_0.GlobalEncoding]));
|
|
WriteLn(Format('ProjectIDGUIDdata1 = $%x', [PublicHeaderBlock_1_0.ProjectIDGUIDdata1]));
|
|
WriteLn(Format('ProjectIDGUIDdata2 = $%x', [PublicHeaderBlock_1_0.ProjectIDGUIDdata2]));
|
|
WriteLn(Format('ProjectIDGUIDdata3 = $%x', [PublicHeaderBlock_1_0.ProjectIDGUIDdata3]));
|
|
// WriteLn(Format('ProjectIDGUIDdata4 = %x', [ProjectIDGUIDdata2]));
|
|
WriteLn(Format('VersionMajor = %d', [PublicHeaderBlock_1_0.VersionMajor]));
|
|
WriteLn(Format('VersionMinor = %d', [PublicHeaderBlock_1_0.VersionMinor]));
|
|
WriteLn(Format('SystemIdentifier = %s', [PublicHeaderBlock_1_0.SystemIdentifier]));
|
|
WriteLn(Format('GeneratingSoftware = %s', [PublicHeaderBlock_1_0.GeneratingSoftware]));
|
|
WriteLn(Format('FileCreationDayofYear = %d', [PublicHeaderBlock_1_0.FileCreationDayofYear]));
|
|
WriteLn(Format('FileCreationYear = %d', [PublicHeaderBlock_1_0.FileCreationYear]));
|
|
WriteLn(Format('HeaderSize = $%x', [PublicHeaderBlock_1_0.HeaderSize]));
|
|
WriteLn(Format('OffsetToPointData = $%x', [PublicHeaderBlock_1_0.OffsetToPointData]));
|
|
WriteLn(Format('NumberofVariableLengthRecords = $%x', [PublicHeaderBlock_1_0.NumberofVariableLengthRecords]));
|
|
WriteLn(Format('PointDataFormatID = $%x', [PublicHeaderBlock_1_0.PointDataFormatID]));
|
|
WriteLn(Format('PointDataRecordLength = $%x', [PublicHeaderBlock_1_0.PointDataRecordLength]));
|
|
WriteLn(Format('Numberofpointrecords = $%x', [PublicHeaderBlock_1_0.Numberofpointrecords]));
|
|
WriteLn(Format('Numberofpointsbyreturn = %x %x %x %x %x',
|
|
[PublicHeaderBlock_1_0.Numberofpointsbyreturn[0],
|
|
PublicHeaderBlock_1_0.Numberofpointsbyreturn[1],
|
|
PublicHeaderBlock_1_0.Numberofpointsbyreturn[2],
|
|
PublicHeaderBlock_1_0.Numberofpointsbyreturn[3],
|
|
PublicHeaderBlock_1_0.Numberofpointsbyreturn[4]
|
|
]));
|
|
WriteLn(Format('Xscalefactor = %f', [PublicHeaderBlock_1_0.Xscalefactor]));
|
|
WriteLn(Format('Yscalefactor = %f', [PublicHeaderBlock_1_0.Yscalefactor]));
|
|
WriteLn(Format('Zscalefactor = %f', [PublicHeaderBlock_1_0.Zscalefactor]));
|
|
WriteLn(Format('Xoffset = %f', [PublicHeaderBlock_1_0.Xoffset]));
|
|
WriteLn(Format('Yoffset = %f', [PublicHeaderBlock_1_0.Yoffset]));
|
|
WriteLn(Format('Zoffset = %f', [PublicHeaderBlock_1_0.Zoffset]));
|
|
WriteLn(Format('MaxX = %f', [PublicHeaderBlock_1_0.MaxX]));
|
|
WriteLn(Format('MinX = %f', [PublicHeaderBlock_1_0.MinX]));
|
|
WriteLn(Format('MaxY = %f', [PublicHeaderBlock_1_0.MaxY]));
|
|
WriteLn(Format('MinY = %f', [PublicHeaderBlock_1_0.MinY]));
|
|
WriteLn(Format('MaxZ = %f', [PublicHeaderBlock_1_0.MaxZ]));
|
|
WriteLn(Format('MinZ = %f', [PublicHeaderBlock_1_0.MinZ]));
|
|
WriteLn('');
|
|
WriteLn(Format('LAS 1.0 header size = $%x', [SizeOf(TLASPublicHeaderBlock_1_0)]));
|
|
WriteLn('');
|
|
end;
|
|
{$endif}
|
|
|
|
procedure TvLASVectorialReader.ReadVariableLengthRecords(AStream: TStream);
|
|
var
|
|
i: Integer;
|
|
NextPosition: Int64;
|
|
begin
|
|
NextPosition := PositionAfterPublicHeader;
|
|
|
|
SetLength(VariableLengthRecords, PublicHeaderBlock_1_0.NumberofVariableLengthRecords);
|
|
for i := 0 to PublicHeaderBlock_1_0.NumberofVariableLengthRecords - 1 do
|
|
begin
|
|
AStream.Position := NextPosition;
|
|
{$ifdef FPVECTORIALDEBUG_LAS}
|
|
WriteLn(Format('Variable Length Record #%d Position = $%x', [i, NextPosition]));
|
|
WriteLn('');
|
|
{$endif}
|
|
AStream.Read(VariableLengthRecords[i], SizeOf(TLASVariableLengthRecord));
|
|
NextPosition := AStream.Position+VariableLengthRecords[i].RecordLengthAfterHeader;
|
|
{$ifdef FPVECTORIALDEBUG_LAS}
|
|
WriteLn(Format('RecordSignatureAABB = $%x', [VariableLengthRecords[i].RecordSignatureAABB]));
|
|
WriteLn(Format('UserID = %s', [VariableLengthRecords[i].UserID]));
|
|
WriteLn(Format('RecordID = $%x', [VariableLengthRecords[i].RecordID]));
|
|
WriteLn(Format('RecordLengthAfterHeader = $%x', [VariableLengthRecords[i].RecordLengthAfterHeader]));
|
|
WriteLn(Format('Description = %s', [VariableLengthRecords[i].Description]));
|
|
WriteLn('');
|
|
{$endif}
|
|
end;
|
|
end;
|
|
|
|
procedure TvLASVectorialReader.ReadFromStream(AStream: TStream;
|
|
AData: TvVectorialDocument);
|
|
begin
|
|
// First read the header like if it was for LAS 1.0,
|
|
// this will tell us the real version so then we read it again
|
|
InitialPos := AStream.Position;
|
|
AStream.Read(PublicHeaderBlock_1_0, SizeOf(TLASPublicHeaderBlock_1_0));
|
|
{$ifdef FPVECTORIALDEBUG_LAS}
|
|
DebugOutPublicHeaderBlock();
|
|
{$endif}
|
|
|
|
// First check the signature
|
|
if PublicHeaderBlock_1_0.FileSignatureLASF <> 'LASF' then
|
|
raise Exception.Create('[TvLASVectorialReader.ReadFromStream] Invalid file signoture while reading LAS file');
|
|
|
|
// In LAS 1.3+ read the header extension
|
|
// ToDo
|
|
|
|
PositionAfterPublicHeader := AStream.Position;
|
|
|
|
// Read the variable length records
|
|
ReadVariableLengthRecords(AStream);
|
|
|
|
// Read the point data
|
|
AStream.Position := InitialPos + PublicHeaderBlock_1_0.OffsetToPointData;
|
|
case PublicHeaderBlock_1_0.PointDataFormatID of
|
|
0:
|
|
begin
|
|
|
|
end;
|
|
1:
|
|
begin
|
|
end;
|
|
end;
|
|
end;
|
|
|
|
initialization
|
|
|
|
RegisterVectorialReader(TvLASVectorialReader, vfLAS);
|
|
|
|
end.
|
|
|