Vr Mapping |
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LAS Out (LasOut)
Type: Translator
Translates Vr Points to the LAS (LiDAR Archive Standard) format.
The LAS file format is a public file format for the interchange of LiDAR data between computer systems. This binary file format consists of point coordinate data along with up to 16 attributes per point. The LAS In and LAS Out translators provided maintain these attributes in the Vr Mapping database. The translation of LAS data to and from the Vr Mapping database requires very few parameters. The LAS translators are based on the LAS Specification Version 1.2 which was approved by the ASPRS board on September 2nd, 2008.
LiDAR points are stored as Vr Points and maintain LAS defined point attributes.
Loads previously recorded Las Out (.lao) parameter file.
Records current translation parameters to a Las Out (.lao) parameter file.
Edits the LAS file header that will be used when creating LAS files.
The Define LAS Header dialog box
File Source ID
File Source ID (Flight Line Number if this file was derived from an original flight line): This field should be set to a value between 1 and 65,535, inclusive. A value of zero (0) is interpreted to mean that an ID has not been assigned. In this case, processing software is free to assign any valid number. Note that this scheme allows a LiDAR project to contain up to 65,535 unique sources. A source can be considered an original flight line or it can be the result of merge and/or extract operations.
GPS Time Type
The meaning of GPS Time in the Point Records. 0 (not set) -> GPS time in the point record fields is GPS Week Time (the same as previous versions of LAS) 1 (set) -> GPS Time is standard GPS Time (satellite GPS Time) minus 1 x 109. The offset moves the time back to near zero to improve floating point resolution.
Project ID (GUID)
Project ID (GUID data): The four fields that comprise a complete Globally Unique Identifier (GUID) are now reserved for use as a Project Identifier (Project ID). The field remains optional. The time of assignment of the Project ID is at the discretion of processing software. The Project ID should be the same for all files that are associated with a unique project. By assigning a Project ID and using a File Source ID (defined above) every file within a project and every point within a file can be uniquely identified, globally.
Point Format
The point data format ID corresponds to the point data record format type. LAS 1.2 defines types 0, 1, 2 and 3. Following are the attributes included in each format as defined by the LAS Specification 1.2.
| • | Format 0 - X, Y, Z, Intensity, Return Number, Number of Returns, Scan Direction Flag, Edge of Flight Flag, Classification, Scan Angle Rank, User Data, Point Source ID |
| • | Format 1 - X, Y, Z, Intensity, Return Number, Number of Returns, Scan Direction Flag, Edge of Flight Flag, Classification, Scan Angle Rank, User Data, Point Source ID, GPS Time |
| • | Format 2 - X, Y, Z, Intensity, Return Number, Number of Returns, Scan Direction Flag, Edge of Flight Flag, Classification, Scan Angle Rank, User Data, Point Source ID, Red, Green, Blue |
| • | Format 3 - X, Y, Z, Intensity, Return Number, Number of Returns, Scan Direction Flag, Edge of Flight Flag, Classification, Scan Angle Rank, User Data, Point Source ID, GPS Time, Red, Green, Blue |
See the Vr Point format for more information on these fields and any differences between the Vr Point format and the LAS specification.
Allows editing of general translation parameters.
The Edit Parameters dialog Box
Workspaces to consider
Defines the workspaces to consider when running exporting LAS files. Options are Current workspace or All open workspaces.
Translation file mode
Defines the handling of output files during translation which include the following options.
| • | Single File - All open workspaces will be translated into a single LAS file. The "Output file name" field will determine the LAS file name. |
| • | One File Per Workspace - An LAS file will be created for each open workspace. The LAS filename will be the same as the workspace (VrOne) filename with an .las extension. The "Output directory" field may be used to place the LAS files in a different folder than the VrOne file. |
Output file name
Defines the output file name when "Translation file mode" is set to "Single File". This name is ignored if "Translation file mode" is set to "One file Per Workspace"
Output directory
Output directory if not using "Single File" translation mode. This field may be left blank to place the LAS files in same the directory as the VrOne files. This field is ignored if the "Translation file mode" is set to "Single File".
Output Symbols
Typically the LAS Out translator exports Vr Points but Symbols may also be output. Symbols do not carry the LiDAR attributes that Vr Points have and default values will be used for these attributes for each symbol.
Output Points
Typically the LAS Out translator exports Vr Points and this parameter is normally set to Yes.
Layers to translate
Defines the layers to translate to LAS. If a layer is specified it will be translated even if it is turned off in VrOne/VrTwo.
Translate deleted points
One of the attributes stored with each Vr Point is a delete flag which allows points in the database to be marked as deleted. If this parameter is selected then deleted points will be translated. Deleted points that are translated with retain the delete flag in the LAS output file.
Decimal Accuracy for coordinates
This parameter defines the decimal accuracy for the coordinates. When point coordinates are stored in a LAS file, a scale factor and offset are applied. If the decimal accuracy is too high it will be reduced automatically.
Begins the file translation process.
The Translation information box
Starts the browser and displays the current help document.
Quits Las Out and gives an option to save the current parameters if they have been changed.