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LASwriteItemCompressed_POINT10_v2.cs
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LASwriteItemCompressed_POINT10_v2.cs
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//===============================================================================
//
// FILE: laswriteitemcompressed_point10_v2.cs
//
// CONTENTS:
//
// Implementation of LASwriteItemCompressed for POINT10 items (version 2).
//
// PROGRAMMERS:
//
// [email protected] - http://rapidlasso.com
//
// COPYRIGHT:
//
// (c) 2005-2012, martin isenburg, rapidlasso - tools to catch reality
// (c) of the C# port 2014 by Shinta <[email protected]>
//
// This is free software; you can redistribute and/or modify it under the
// terms of the GNU Lesser General Licence as published by the Free Software
// Foundation. See the COPYING file for more information.
//
// This software is distributed WITHOUT ANY WARRANTY and without even the
// implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
//
// CHANGE HISTORY: omitted for easier Copy&Paste (pls see the original)
//
//===============================================================================
using System.Diagnostics;
using System.Runtime.InteropServices;
namespace laszip.net
{
class LASwriteItemCompressed_POINT10_v2 : LASwriteItemCompressed
{
[StructLayout(LayoutKind.Sequential, Pack=1)]
struct LASpoint10
{
public int x;
public int y;
public int z;
public ushort intensity;
// all these bits combine to flags
//public byte return_number : 3;
//public byte number_of_returns_of_given_pulse : 3;
//public byte scan_direction_flag : 1;
//public byte edge_of_flight_line : 1;
public byte flags;
public byte classification;
public sbyte scan_angle_rank;
public byte user_data;
public ushort point_source_ID;
}
public LASwriteItemCompressed_POINT10_v2(ArithmeticEncoder enc)
{
// set encoder
Debug.Assert(enc!=null);
this.enc=enc;
// create models and integer compressors
ic_dx=new IntegerCompressor(enc, 32, 2); // 32 bits, 2 context
ic_dy=new IntegerCompressor(enc, 32, 22); // 32 bits, 22 contexts
ic_z=new IntegerCompressor(enc, 32, 20); // 32 bits, 20 contexts
ic_intensity=new IntegerCompressor(enc, 16, 4);
m_scan_angle_rank[0]=enc.createSymbolModel(256);
m_scan_angle_rank[1]=enc.createSymbolModel(256);
ic_point_source_ID=new IntegerCompressor(enc, 16);
m_changed_values=enc.createSymbolModel(64);
for(int i=0; i<256; i++)
{
m_bit_byte[i]=null;
m_classification[i]=null;
m_user_data[i]=null;
}
}
public override bool init(laszip_point item)
{
// init state
for(int i=0; i<16; i++)
{
last_x_diff_median5[i].init();
last_y_diff_median5[i].init();
last_intensity[i]=0;
last_height[i/2]=0;
}
// init models and integer compressors
ic_dx.initCompressor();
ic_dy.initCompressor();
ic_z.initCompressor();
ic_intensity.initCompressor();
enc.initSymbolModel(m_scan_angle_rank[0]);
enc.initSymbolModel(m_scan_angle_rank[1]);
ic_point_source_ID.initCompressor();
enc.initSymbolModel(m_changed_values);
for(int i=0; i<256; i++)
{
if(m_bit_byte[i]!=null) enc.initSymbolModel(m_bit_byte[i]);
if(m_classification[i]!=null) enc.initSymbolModel(m_classification[i]);
if(m_user_data[i]!=null) enc.initSymbolModel(m_user_data[i]);
}
// init last item
last.x=item.X;
last.y=item.Y;
last.z=item.Z;
last.intensity=0; // but set intensity to zero
last.flags=item.flags;
last.classification=item.classification;
last.scan_angle_rank=item.scan_angle_rank;
last.user_data=item.user_data;
last.point_source_ID=item.point_source_ID;
return true;
}
public override bool write(laszip_point item)
{
uint r=item.return_number;
uint n=item.number_of_returns_of_given_pulse;
uint m=Laszip_Common_v2.number_return_map[n, r];
uint l=Laszip_Common_v2.number_return_level[n, r];
// compress which other values have changed
uint changed_values=0;
bool needFlags=last.flags!=item.flags; if(needFlags) changed_values|=32; // bit_byte
bool needIntensity=last_intensity[m]!=item.intensity; if(needIntensity) changed_values|=16;
bool needClassification=last.classification!=item.classification; if(needClassification) changed_values|=8;
bool needScanAngleRank=last.scan_angle_rank!=item.scan_angle_rank; if(needScanAngleRank) changed_values|=4;
bool needUserData=last.user_data!=item.user_data; if(needUserData) changed_values|=2;
bool needPointSourceID=last.point_source_ID!=item.point_source_ID; if(needPointSourceID) changed_values|=1;
enc.encodeSymbol(m_changed_values, changed_values);
// compress the bit_byte (edge_of_flight_line, scan_direction_flag, returns, ...) if it has changed
if(needFlags)
{
if(m_bit_byte[last.flags]==null)
{
m_bit_byte[last.flags]=enc.createSymbolModel(256);
enc.initSymbolModel(m_bit_byte[last.flags]);
}
enc.encodeSymbol(m_bit_byte[last.flags], item.flags);
}
// compress the intensity if it has changed
if(needIntensity)
{
ic_intensity.compress(last_intensity[m], item.intensity, (m<3?m:3u));
last_intensity[m]=item.intensity;
}
// compress the classification ... if it has changed
if(needClassification)
{
if(m_classification[last.classification]==null)
{
m_classification[last.classification]=enc.createSymbolModel(256);
enc.initSymbolModel(m_classification[last.classification]);
}
enc.encodeSymbol(m_classification[last.classification], item.classification);
}
// compress the scan_angle_rank ... if it has changed
if(needScanAngleRank)
{
enc.encodeSymbol(m_scan_angle_rank[item.scan_direction_flag], (uint)MyDefs.U8_FOLD(item.scan_angle_rank-last.scan_angle_rank));
}
// compress the user_data ... if it has changed
if(needUserData)
{
if(m_user_data[last.user_data]==null)
{
m_user_data[last.user_data]=enc.createSymbolModel(256);
enc.initSymbolModel(m_user_data[last.user_data]);
}
enc.encodeSymbol(m_user_data[last.user_data], item.user_data);
}
// compress the point_source_ID ... if it has changed
if(needPointSourceID)
{
ic_point_source_ID.compress(last.point_source_ID, item.point_source_ID);
}
// compress x coordinate
int median=last_x_diff_median5[m].get();
int diff=item.X-last.x;
ic_dx.compress(median, diff, n==1?1u:0u);
last_x_diff_median5[m].add(diff);
// compress y coordinate
uint k_bits=ic_dx.getK();
median=last_y_diff_median5[m].get();
diff=item.Y-last.y;
ic_dy.compress(median, diff, (n==1?1u:0u)+(k_bits<20?k_bits&0xFEu:20u)); // &0xFE round k_bits to next even number
last_y_diff_median5[m].add(diff);
// compress z coordinate
k_bits=(ic_dx.getK()+ic_dy.getK())/2;
ic_z.compress(last_height[l], item.Z, (n==1?1u:0u)+(k_bits<18?k_bits&0xFEu:18u)); // &0xFE round k_bits to next even number
last_height[l]=item.Z;
// copy the last point
last.x=item.X;
last.y=item.Y;
last.z=item.Z;
last.intensity=item.intensity;
last.flags=item.flags;
last.classification=item.classification;
last.scan_angle_rank=item.scan_angle_rank;
last.user_data=item.user_data;
last.point_source_ID=item.point_source_ID;
return true;
}
ArithmeticEncoder enc;
LASpoint10 last=new LASpoint10();
ushort[] last_intensity=new ushort[16];
StreamingMedian5[] last_x_diff_median5=new StreamingMedian5[16];
StreamingMedian5[] last_y_diff_median5=new StreamingMedian5[16];
int[] last_height=new int[8];
IntegerCompressor ic_dx;
IntegerCompressor ic_dy;
IntegerCompressor ic_z;
IntegerCompressor ic_intensity;
IntegerCompressor ic_point_source_ID;
ArithmeticModel m_changed_values;
ArithmeticModel[] m_scan_angle_rank=new ArithmeticModel[2];
ArithmeticModel[] m_bit_byte=new ArithmeticModel[256];
ArithmeticModel[] m_classification=new ArithmeticModel[256];
ArithmeticModel[] m_user_data=new ArithmeticModel[256];
}
}