Lidar (Light Detection and Ranging) uses optical remote
sensing technology that can measure the distance of a target by illuminating the
target using pulses from a laser.

Aerial 3D Lidar data is available to NHDOT staff. The Lidar
files (.LAS) are stored in N:\Aerials\2010\LIDAR\.

To see which files are available in your project area, attach N:\cadd\cadd\GIS_To_MicrostationV8\lidar-index.dgn as a
reference file. This can be done in MX v8i or in MicroStation.
Be sure to select the Coincident-World orientation
when attaching the file.

If files are available for the desired area, a rectangle
with the file name will be displayed. The text contains the name of the
file. For example: 0900002250.las refers to the file N:\Aerials\2010\LIDAR\0900002250.LAS, just simply write down the file names displayed on this reference file.

3. From the Open file panel, navigate to N:\Aerials\2010 LIDAR\ and
open the desired file. The Lidar LAS panel shown below
allows control of data filtering prior to loading into Data Acquisition.

4. There are multiple data classifications offered in a Lidar file. In the Selected Features section of the
Lidar LAS dialog, choose the
classifications you wish to import (such as Ground). Next, select the
Filter settings to be used for
this
import.

For one or two sections use the Tile Filter with Z Tolerance set to
0.2.

If you are intending to import multiple files use the Tin Filter
set to Fine.

The Filter button will give an estimate of the percent
Reduction, however it is not a necessary step for this process. Click
the Accept button to import the Lidar file. Note that it might take some time
to process and if you are importing
several files it may crash your session.

From the Data Acquisition panel, expand the Surfaces
branch to see the imported Lidar files. To display a file, check the box next to
file entry. Consider that his takes time and memory. Repeat
steps 3 and 4 for each Lidar file desired.

5. After importing each surface, they should be clipped
down to the project's extent. Draw a Closed Element around the project and select it with the Element Selection
tool. Right-click on the imported surface and select Clip by Polygon...
> External. Clip all imported surfaces.

6. Next the surfaces need to be combined. Right-click
Surfaces
> Create Surfaces > Empty Surface to create an empty
(receiving) surface for combining the individual surfaces. Right-Click
this new surface (Surface X) and use Append From...>
to combine each surface into
it.

8. The receiving surface can be renamed by using the Data Acquisitions Details
box. Highlight the name and key in a new one (such as TRIANGLESLIDAR). The
name will update in the Data Acquisition panel. To create MX
triangle strings, the combined
surface must be exported to the MX Model file. Right-click on the renamed
surface and select Export to... > MX modelfile, then select the
project's model file and click Save.

Close the Data Acquisition
tools and continue with your design. Your Lidar surface is now an MX triangle model.
Set the Model Defaults to MFW
Triangulation.pts & MFW Triangulation.fns. Consider Trimming
these triangles to eliminate triangles from spanning void regions. From
the Analysis menu, select Triangle > Trim Triangulation...
Refer
to MX Triangulation for details on Triangle
Trimming.

For additional information on the Data Acquisition tool open
the help file C:\Program Files\Bentley\MX V8i\Documentation\Civilmaster.chm