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{
lazvectorialreader.pas
Reads geospatial data encoded in the ASPRS LASer (LAS) file format version 1.3
With compression
LAZ file format specification obtained from:
http://laszip.org/
http://www.cs.unc.edu/~isenburg/lastools/download/laszip.pdf
Example file:
www.cs.unc.edu/~isenburg/lastools/download/data/xyzrgb_manuscript.laz
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 lazvectorialreader;
{$ifdef fpc}
{$mode delphi}
{$endif}
{$define FPVECTORIALDEBUG_LAS}
interface
uses
Classes, SysUtils, dateutils,
fpcanvas, fpimage,
//avisozlib,
fpvectorial, lasvectorialreader;
type
{ TvLAZVectorialReader }
TvLAZVectorialReader = class(TvLASVectorialReader)
public
{ General reading methods }
//procedure ReadFromStream(AStream: TStream; AData: TvVectorialDocument); override;
end;
implementation
(*procedure TvLAZVectorialReader.ReadFromStream(AStream: TStream;
AData: TvVectorialDocument);
var
lPage: TvVectorialPage;
lRecord0: TLASPointDataRecordFormat0;
lRecord1: TLASPointDataRecordFormat1;
lFirstPoint: Boolean = True;
lPoint: TvPoint;
lClassification: Integer = -1;
lColor: TFPColor;
lPointsCounter: Integer = 0;
begin
// Clear and add the first page
AData.Clear;
lPage := AData.AddPage();
(* // 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');
lPage.MinX := PublicHeaderBlock_1_0.MinX;
lPage.MinY := PublicHeaderBlock_1_0.MinY;
lPage.MinZ := PublicHeaderBlock_1_0.MinZ;
lPage.MaxX := PublicHeaderBlock_1_0.MaxX;
lPage.MaxY := PublicHeaderBlock_1_0.MaxY;
lPage.MaxZ := PublicHeaderBlock_1_0.MaxZ;
// 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;
while AStream.Position < AStream.Size do
begin
// Send a progress event every 1k points
Inc(lPointsCounter);
if lPointsCounter mod 1000 = 0 then
DoProgress(Round(AStream.Position * 100 / AStream.Size), AData);
// hack to cut las files: if lPage.GetEntitiesCount = 100000 then Exit;
case PublicHeaderBlock_1_0.PointDataFormatID of
0:
begin
AStream.ReadBuffer(lRecord0, SizeOf(TLASPointDataRecordFormat0));
lClassification := lRecord0.Classification;
lPoint := lPage.AddPoint(lRecord0.X, lRecord0.Y, lRecord0.Z);
end;
1:
begin
AStream.ReadBuffer(lRecord1, SizeOf(TLASPointDataRecordFormat1));
lClassification := lRecord1.Classification;
lPoint := lPage.AddPoint(lRecord1.X, lRecord1.Y, lRecord1.Z);
end;
end;
// Correct the min and max
if lFirstPoint then
begin
lPage.MinX := lPoint.X;
lPage.MinY := lPoint.Y;
lPage.MinZ := lPoint.Z;
lPage.MaxX := lPoint.X;
lPage.MaxY := lPoint.Y;
lPage.MaxZ := lPoint.Z;
lFirstPoint := False;
end
else
begin
if lPage.MinX > lPoint.X then lPage.MinX := lPoint.X;
if lPage.MinY > lPoint.Y then lPage.MinY := lPoint.Y;
if lPage.MinZ > lPoint.Z then lPage.MinZ := lPoint.Z;
if lPage.MaxX < lPoint.X then lPage.MaxX := lPoint.X;
if lPage.MaxY < lPoint.Y then lPage.MaxY := lPoint.Y;
if lPage.MaxZ < lPoint.Z then lPage.MaxZ := lPoint.Z;
end;
// Set a color if desired
case lClassification of
// Table 4.9 - ASPRS Standard LIDAR Point Classes
// Classification Value
// 0 Created, never classified
// 1 Unclassified1
// 2 Ground
2: lColor := colMaroon;
// 3 Low Vegetation
3: lColor := colGreen;
// 4 Medium Vegetation
4: lColor := colGreen;
// 5 High Vegetation
5: lColor := colDkGreen;
// 6 Building
6: lColor := colGray;
// 7 Low Point (noise)
// 8 Model Key-point (mass point)
// 9 Water
9: lColor := colBlue;
else
lColor := colBlack;
end;
lPoint.Pen.Color := lColor;
end;
end;*)
initialization
// RegisterVectorialReader(TvLAZVectorialReader, vfLAZ);
// RegisterVectorialWriter(TvLAZVectorialWriter, vfLAZ);
end.
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