Add mesh from LAS file

Toolbar:

Menu: CAD-Earth > Mesh > Mesh Explorer.

Mesh Explorer node:

Context Menu: Add Terrain Mesh > From File > LAS file

Command line: CE_MESHEXPLORER

CAD-Earth version: Premium.

Command description:

Import a terrain mesh from a LAS file specifying mesh properties and refinement options and other processing parameters, with the option to process the entire file or to select the area to process.

ØMesh properties. The following dialog box will be shown:

•Name. Enter text to identify the mesh. Must not contain the following characters: | * : ; > < ? , = ` \

•Description. Enter additional information about the mesh (optional).

•Color. Select the color for the mesh lines and points.

•Layer. Select the layer where the mesh will be created.

•Visualization mode. The mesh can be displayed in any of the following visualization modes:

•TIN: Mesh triangles with continuous lines.

•Points: Mesh vertices will be shown as simple points with no size.

•Boundary & Points: Triangle sides that are not adjoined to another triangle will be shown. Internal vertices will be displayed as simple points with no size.

•Boundary Only: Only triangle sides that are not adjoined to another triangle will be shown, creating one or several outlines.

•Linear units. The distance unit selected will define the mesh scale factor. If the required unit is not included in the list, you can select 'Custom' at the end of the list to define a unit conversion factor.

•Linear unit to m factor. The units of measure used by CAD-Earth are meters, which are converted to the unit selected using this factor to display distance, area and volume calculations.

ØMesh refinement options. The following dialog box will be shown:

ØRefine mesh boundary. Triangles on the mesh boundary will be removed according to the parameters specified.

•Minimum triangle internal angle. (Decimal degrees) Triangles that have a vertex with an internal angle less or equal to the value specified, will be removed.

•Maximum triangle side length. (Drawing units) Triangles that have a side equal to or greater than the value specified, will be removed.

ØRemove coplanar points.

•Maximum slope deviation. If the average slope of a vertex is equal or higher than this value, the vertex will be removed.

•Maximum distance from point to plane. If the distance from a vertex to an average plane is higher than this value, the vertex will be removed.

•Maximum number of iterations. If the number of iterations is equal to this value, the mesh decimation will stop.

•Maximum percent reduction. If the percent reduction reaches this value, the mesh decimation will stop.

ØRemove nearby points. If this option is checked, points will have a distance between them equal to or higher than the minimum value specified.

ØRemove vegetation and building points. If this option is checked, at intervals of the scan distance specified, the point with minimum elevation inside a square the size of the filter distance will be found and considered to be a ground point.

ØLAS file.

•Name. The current name of the file being processed. If you select the info button, the file properties will be displayed, showing the file path, LIDAR, and the georeference parameters.

ØLinear units in file. The EPSG unit code and description are shown.

ØPath type. The path to the LAS file can be as follows:

•Full path. The file must be located in the path selected.

•Relative path. The file must be located in a subfolder or in a parent folder relative to where the drawing file is saved.

•No path. The file must be located in the same path as the drawing or in any of the support file paths.

ØRead data every n points. Only points at the specified interval will be processed.

ØGeoreference drawing from file. Georeference information in file will be used to georeference the current drawing.

ØFile processing.

•Process entire file. All the points in file will be processed.

•Select area to process. The following LAS viewer will be shown, where you can select a polygonal or rectangular region to process, or you can select an existing closed polyline in the drawing to define the area:

Button	Description
	Select polygonal region. Specify points on screen to define the area to process.
	Select rectangular region. Specify two corners on screen to define the rectangular area to process.
	Select closed polyline in drawing. Pick an existing closed polyline to define the area to process.
	Clear selection. Delete the area defined.
	Show/Hide cloud points. If you hide the mesh, you can see the current area defined more clearly.
	Pan view. If you keep the left mouse button pressed and move the mouse pointer, the view will slide to the second point direction.
	Show view extents. Back to the original view.
	Increase zoom. The view will be incremented about 5% every time you pick this button.
	Decrease zoom. The view will be decremented about 5% every time you pick this button.
	Exposure and contrast. Increase or decrease the amount of light and color saturation.

ØPoint record filtering. The following dialog box will be shown. Only points having the filter attributes selected will be processed.

ØPoint attributes. If the LAS file has points with the selected attributes defined, only the points with those attributes checked will be processed.

ØCustom codes. If you select the 'Custom defined' point attribute, you can type in this box the attribute code numbers separated by commas.

ØPoint returns. Only points with an intensity and scanning angle within the specified range will be processed.

ØIntensity and scan angle. Only points with intensity between the range specified will be processed.

Tips:

•If the index file is not present in the LAS file folder, a message will display to confirm if you wish to create it. This index file will speed up the point searching in the LAS file, avoiding reading the entire file to search for points. The index file will have the same name as the LAS file but with a lax extension. The index file will take several minutes to be created, but it will be created only once.

•The LAS file preview is not displayed at full resolution. A maximum of one hundred thousand points will be sampled from the LAS file to display the information quickly.

•A file with the same name as the LAS file, but with a lasview extension, will be created in the same folder where the LAS file is located to allow instant preview the next time the file is processed.

•Some LAS files are several gigabytes in size. Select only the LAS file area you are going to process and scan the file every 5 or 10 points to reduce the final mesh size. You can also set mesh refinement parameters to reduce the number of mesh vertices.

•The area to process can be defined in a clockwise or counter-clockwise direction.

•If you select a closed polyline to define the area to process, it must be placed in the drawing's correct coordinates before using this command.

•You can use the mouse wheel to increase or decrease the view when selecting an area to process. The view will be resized according to where the current cursor is located.

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