Insert terrain mesh from Google Earth

Toolbar:

Menu: CAD-Earth > Mesh commands > Insert terrain mesh from Google Earth

Command line: CE_INSGEMESH

CAD-Earth version: Plus, Premium.

Command description:

A terrain mesh can be created inside an existing Google Earth polygon or path calculating point elevations using this command. By specifying the grid rotation angle and mesh resolution (normal, medium, high, highest) the mesh density and precision can be adjusted. The resulting mesh can be processed to obtain contour lines, dynamic profile and section drawings complete with annotations.

You don't have to georeference your drawing before using this command because the mesh will be created selecting an existing Google Earth polygon which already contains geographic information.

A dialog box will be displayed where you can select the polygon to define the mesh extents.

Terrain mesh obtained from Google Earth (isometric view)

Dialog box settings (Mesh tab):

Insert terrain mesh from Google Earth (Mesh tab)

ØMesh generation.

•Create mesh grid inside a closed polygon. A Google Earth polygon must be selected to create the mesh.

•Create mesh grid along a path. An existing Google Earth route must be selected. The distance between stations, offset to the right and left and the distance between sample points, must be provided.

ØMesh along a path.

•Grid resolution. Specify normal, medium, high or highest resolution. The maximum number of screen shots tiled together are:

Resolution	Max. Number of Tiles
Normal	1
Medium	4
High	16
Highest	64

The number of tiles will be adjusted also according to the maximum screen resolution available.

•Grid rotation. You can type a numeric value or select the angle selection button to pick two points in the drawing.

•Distance between stations. Specify the interval distance along the route where the station lines will be placed.

•Distance between points. Specify the interval distance between points that will be placed in each station line.

•Distance to the right. Specify the total distance where the points to the right will be calculated.

•Distance to the left. Specify the total distance where the points to the left will be calculated.

ØTerrain provider. Select to import terrain point elevations from Cesium or directly from Google Earth.

ØLinear units. A conversion factor will be applied to scale the mesh according to the units selected.

ØLinear unit to meter factor. When you select an insertion unit the corresponding conversion to meter factor will be displayed. If you wish to edit the conversion factor you must select the Custom unit from the list.

Dialog box settings (Settings tab):

Insert terrain mesh from Google Earth (Settings tab)

ØMesh properties.

•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 which 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 which are not adjoined to another triangle will be shown, creating one or several outlines.

ØCurve smoothness. If the closed polyline has curved sides they will be converted to straight segments before the polygon is added to Google Earth. The number of resulting segments will be proportional to the maximum segment length and the maximum deflection angle between consecutive segments.

ØShow place in Google Earth. After the mesh triangles are created, Google Earth will automatically be activated and zoomed to the place where the mesh is physically located. A folder will be added to Google Earth's temporary places containing the polygon representing the mesh outline.

ØShow grid lines in Google Earth. Routes will be added to the mesh folder in Google Earth's temporary places for each mesh line processed.

ØShow mesh in 3D Viewer. The Mesh 3D Viewer will be opened showing the mesh with the image from Google Earth and lighting applied.

ØLink image to Google Earth. Screenshots will be taken when sampling surface points in Google Earth to project the final image into the mesh. A file with DDX extension will be created containing image information. The path to this file can be the following:

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

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

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

ØSave image within drawing file. If this option is checked, the image data will be saved within the mesh, and you will not be asked to save the image file, and the path type selection list (full, relative, no path) will be disabled.

Dialog box to select Google Earth polygon

Tips:

•If you need to place the mesh in the corresponding UTM coordinates according to a coordinate system you must use the command to import a terrain mesh instead.

•NOTE: If you select to get terrain point elevations directly from Google Earth, you must install v7.3.2 64-bit from this link. Google Earth v7.3.3 and above, doesn't expose a programming interface, so it's not compatible with CAD-Earth. To avoid Google Earth being changed to another version, please rename the file C:\Program Files (x86)\Google\Update\GoogleUpdate.exe to C:\Program Files (x86)\Google\Update\GoogleUpdateBackup.exe. Google Earth has a limit of 5000 points per session. If the mesh has more than 5000 points, Google Earth will be automatically restarted.

•If you press ENTER instead of picking an insertion point the mesh will be placed in the corresponding WGS84 UTM coordinates in the drawing. If the terrain mesh is not shown you can use the AutoCAD ZOOM EXTENTS command to display it on the screen.

•If you open the drawing containing the mesh in another computer, the corresponding DDX file must be located according to the path type selected (at the full or relative path or in the same path as the drawing file). If the other computer doesn't have CAD-Earth installed, you must include the file CVLC_PointGroup.dbx (located in the CAD-Earth installation folder) in the same path as the drawing and load it with the APPLOAD command.

•You can use the AutoCAD EXPLODE command to convert the mesh to 3D faces.