Contour plan preparation of desired area using Google earth and QGIS software

Contour Plans as PDF or AutoCAD Drawings

Required Software

• QGIS (free and open-source)
• Google Earth Pro (free)
• AutoCAD (optional – required only if you need to edit the output in AutoCAD)

Step-by-Step Guide

1. Open Google Earth Pro
2. Go to the desired location
   Enter coordinates (if known) or search by place name. Use the mouse to navigate to the exact area you need.
3. Draw the boundary path
   Use the “Add Path” tool to draw lines around the area, adding as many points as possible for better accuracy. Save the path as a KMZ file.
4. Add elevation data using GPS Visualizer
   Go to gpsvisualizer.com/elevation. Upload the KMZ file, select “Plain Text” as output format, and click “Convert and add elevation”.
5. Download the plain text file
6. Create a new project in QGIS
7. Import the text file
   Layer → Add Layer → Add Delimited Text Layer. Select the downloaded file and configure settings as shown.
   Result:
8. Perform Natural Neighbor interpolation
   Open Processing Toolbox → search “Natural Neighbor”.
   Set parameters (e.g., cell size 0.0005):
9. Generate contours
   Raster → Extraction → Contour. Set interval based on your needs.
   Result:
10. Add labels to contours
    Right-click contour layer → Properties → Labels → select the elevation field (e.g., “ELEV”).

Note: To export for AutoCAD, save the contour layer as DXF.
For PDF output, use QGIS Print Layout/Composer to create and export a high-quality map.

This free workflow allows you to generate accurate contour plans without paid surveying tools.