Using Metric Units in AutoCAD and Land Desktop
Metric: AutoCAD Fundamentals
Metric Units in Modelspace and Paperspace
Block Insertion Scale
Metric Drawing and Project Setup in Land Desktop
Project Conversion: Imperial to Metric
Drawing Size and Scale
Topo and Point Database
Aerial topo in the form of contour lines, 3D polylines, 3D symbols, 3D AutoCAD points, etc. can all be scaled from feet to meters as described above. Softdesk points, however, are at zero elevation . . . their ELEV attribute contains the real elevation of the point. When using the AutoCAD scale command, the x,y,z of the object is scaled but the ELEV attribute will not be.
Open each drawing containing Softdesk point blocks
Use Cogo è Points è Import/Export Points è Export Points to File to send all drawing points out to an ascii text file.
Bring that ascii text file into Lotus or Excel and multiply the ELEV column by .3048. Save the Excel spreadsheet to a DOS text file.
Use Cogo è Points è Import/Export Points è Import Points from File to bring the points back into the drawing with their new elevation. Use the Overwrite option on the import so that the old points will be replaced.
Note: Watch your layers. The points will come in all on the current layer unless you use Description Keys to control their layer by point description.
Digital Terrain Models
DTM files in Softdesk are stored in external databases in X,Y,Z format. Once we scale the project, the x,y,z values will no longer be the same. The TIN files will need to be rebuilt.
For each digital terrain modeling surface, open the drawing in which the topo data is stored.
Use Surface è Open to choose the current DTM surface.
Use Surface è Surface Data è Drawing Point Data è By Selection to select the points to be used in the TIN. Use the Overwrite option.
Use Surface è Surface Data è Edit Faults è Import to import the fault lines for the current surface.
Use the AutoCAD Scale command to scale these fault lines around 0,0,0 by .3048.
Use Surface è Surface Data è Standard Faults è By Polyline to send the new scaled down fault lines to the TIN. Use a fault description of "metric" so we can identify which fault lines are new.
Use Surface è Surface Data è Edit Faults è Delete Faults to delete all fault lines (From File Only) that do not have the new fault description of "metric".
Use Surface è Surface Data è Contour Data to send out any contour lines for use in the TIN.
Use Surface è Build Surface to re-create a metric based TIN from the data.
Note: Any surface editing which was originally performed on the imperial version of the tin will need to be redone on the metric version of the tin. When finished, create contour lines for the new tin to verify its accuracy.
Label new existing ground contour lines with metric interval labels
All bearing and distance labeling will need to be erased and re-created using metric labeling defaults. Also, any dimensions such as street widths, etc. will need to be erased and re-created with metric labeling defaults. Use DDIM to control the default settings for AutoCAD dimensions.
Softdesk stores all horizontal alignment information in x,y,z format so these will need to be updated as well.
For each horizontal alignment, open the required drawing for the horizontal linework
Re-define the alignment with the same name as was used previously, but using desired metric stationing
Use the Align è Stations è Create Stations command to create new metric station labels, erasing the old labels before you begin
Use Align è Stations / Offsets è Label Station / Offset to re-label with new metric stationing any critical points such as intersections, erasing the old labels as you go.
All Softdesk profile information is stored with respect to station. Now that the stations have changed due to the metric environment, these profiles will need to be completely re-created.
For each profile, open the drawing where the profile is stored.
Use Advanced Design è Profile è Select Alignment to choose the appropriate alignment
Use Profile è DTM Surfaces è Select DTM Surface to choose the appropriate existing ground TIN
Use Profile è Existing Ground è Sample from DTM to calculate the eg based on the new TIN
Rename the layer (probably PFGC) to something else temporarily so that information will not be erased
Use Profile è Create Profile è Full Profile to bring in the new profile. Make sure to insert it at the exact same location as the old profile. The routine will erase the old profile for you.
If you used the same vertical exaggeration factor in the new metric scale as you did before, you should be able to scale your proposed information (the linework on what used to be layer PFGC) down by .3048. You will then need to move that linework to the appropriate reference location on the new existing ground profile. Use Profile è Create Profile è List Elevations to verify that the proposed information is at the correct elevation. Then change the name of the layer back to PFGC
Re-define the proposed vertical alignment using Profile è Vertical Alignments è Define FG Centerline
Re-label the profile using Profile è Vertical Alignments è Import
Because of the change in units, all cross-section information will also have to be re-created. Depending on the complexity of the design, the steps required here are too numerous to list in exact detail. We will assume that all users have existing knowledge of the processes involved for section design. Only the primary steps will be listed here.
For each road:
Re-sample the existing ground cross sections
Re-draw and re-define the proposed ground cross section template
Use Design Control to re-input the design parameters for Slopes, Benching, Ditches, and Horizontal and Vertical transition controls.
Erase any old plotted cross sections
Undefine the old cross sections
Plot new cross sections
Re-label any critical information
At this time, the complete roadway should be converted to metric format. Any output you desire such as earthwork quantities, import quantities, finished ground staking points, etc. should automatically be generated in metric units.
The Softdesk Design Module is used to generate plan and profile gravity flow pipes such as sanitary sewers and storm drains. Use Pipes è Unit Settings to change the default settings from Feet to Meters, from CFS to CMS, from Inches to CM, etc.
All pipe information is created based on the lengths of the pipe segments, multiplied by the slopes, to determine inverts, etc. Unfortunately, pipe lengths were originally set based on the stations of the manholes. Now that we have changed the units, the stations have changed. All pipe design information will have to be re-created from scratch.