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Reproject DEM

Overview

The Reproject DEM Tool converts a DEM GeoTIFF from a geographic coordinate system (for example, WGS84 Lat/Long) into the projected coordinate system assigned to your drawing. This makes the DEM align correctly with your CAD geometry, measurements, and other geospatial layers. 

If no coordinate system is assigned to the drawing, SPCAD shows “Coordinate System NOT Assigned,” and the tool will not proceed until you assign one. 

Access 

DEM Tools → Reproject DEM 

When to use the Reproject DEM Tool

Use this tool when you have a DEM GeoTIFF that is: 

  • in Lat/Long (degrees) or other non-projected systems, and 
  • You need it in a projected system (meters/feet) to match your drawing and engineering workflows. 

Typical examples: 

  • DEM downloaded in WGS84 geographic coordinates 
  • DEM from web sources that doesn’t match your project coordinate system 
  • DEM that inserts at an unexpected scale or location due to CRS mismatch 

Prerequisite: Drawing Coordinate System 

Reproject DEM needs your drawing to have a coordinate system assigned. 

  • If the drawing has no coordinate system, SPCAD displays the message: 
    • Coordinate System NOT Assigned 
  • Assign a coordinate system using: 
    • Command: ACS_SP 

Workflow for using Reproject DEM Tool

  1. (If needed) Assign the drawing coordinate system: 
    • Run ACS_SP and select the correct projected coordinate system for your project. 
  2. Run Reproject DEM. 
  3. Browse and select the input GeoTIFF DEM file (the one in geographic / non-projected CRS). 
  4. Choose the output file name and folder. 
  5. SPCAD reprojects the DEM into the drawing’s assigned coordinate system and writes the new GeoTIFF. 

Tips 

  • Always set the coordinate system first: Reprojection is only as correct as the drawing CRS you choose. Make sure your project CRS is correct before creating outputs. 
  • Use projected CRS for design work: Grading, contours, volumes, and distances are more reliable in projected units (meters/feet) than in degrees. 
  • Keep outputs organized: Save reprojected DEMs into a dedicated project folder (e.g., …\Survey\DEM\Reprojected\) so paths stay stable. 
  • Check alignment after reprojection: After inserting/using the reprojected DEM, verify it matches known control points or site boundaries. 
Output 
  • A new reprojected GeoTIFF DEM is saved at the output location you specify, using the same projected coordinate system as the drawing. 

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