convert wgs84 to utm use code

[谢国栋]

I want to convert wgs84 to utm, and I already finish use some code,But  I need to know how to write a las header. such as  utm 49 zone 

I know use txt2las.exe can make this use such command  :txt2las -i "C:\Users\sa759\Documents\LAStools-master\LAStools-master\bin\utm.txt" -parse xyz -olas -utm 49north

Use this command can make it,but I need to use my code to finish this,So how to warite a header?

Thank you very much.

This is my code:

        LASwriter* laswriter;

LASwriteOpener laswriteopener;

LASheader lasheader;

LASpoint laspoint;

lasheader.point_data_format = 1;

lasheader.point_data_record_length = 28;

// init point 

laspoint.init(&lasheader, lasheader.point_data_format, lasheader.point_data_record_length, 0);

// create writer 

laswriteopener.set_file_name(lasfile.c_str());

laswriter = laswriteopener.open(&lasheader);

while (fgets(line, sizeof(line), fp)){

// read txt data  such as Longitude:113 Latitude:23  Height: 10

                result = strtok(line, delims);

lon = atof(result);

result = strtok(NULL, delims);

lat = atof(result);

result = strtok(NULL, delims);

height = atof(result);

zone = static_cast<int>((lon + 180) / 6 + 1);

lat = lat / 180.0*pi;

lon = lon / 180.0*pi;

UTMCoor xy;

LatLonToUTMXY(lat, lon, zone, xy);   // this can convert latitue longtitude to utm x y

double lx, ly, lz;

lx = xy.x; ly = xy.y; lz = height;

fprintf(utm, "%10f,%10f,%10f\n", xy.x, xy.y, height);  //write utm x y height  to a txt file 

laspoint.coordinates[0] = lx;

laspoint.coordinates[1] = ly;

laspoint.coordinates[2] = lz;

laspoint.compute_XYZ();

laswriter->write_point(&laspoint);

laswriter->update_inventory(&laspoint);

}

laswriter->update_header(&lasheader, TRUE);

[Martin Isenburg]

Hello,

you can do this with the LASheader function set_geo_keys()

https://github.com/LAStools/LAStools/blob/master/LASlib/inc/lasdefinitions.hpp#L855

if you can already know the set of keys to use. Alternatively look into the code of geoprojectionconverter.cpp how to put a set of keys together simply by reading the source code of this function here:

https://github.com/LAStools/LAStools/blob/master/src/geoprojectionconverter.cpp#L1280

and here you can see the two used together in action:

https://github.com/LAStools/LAStools/blob/master/src/txt2las.cpp#L671

Regards,

Martin @rapidlasso

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