Simple Way to Make Contour Plan Using AutoCAD and Sketchup

Leveling a site and making it flat might not always be ideal or feasible for construction. Sometimes the contour might be so prominent in a site that it might actually be impossible to level it. In these situations, it is best to use the site's contour to your advantage in design. 

But in order to understand and design a site with contour, you need a model of the contour first. There are several ways to do it. One such method is using AutoCAD and SketchUp.

How To Make A Model Of Contour Using AutoCAD And SketchUp

Step 1: Use Google Earth

• Note down your site coordinates and open them on Google Earth
• Mark the site boundary using the draw tool
• Study the contour

Step 2: Export To AutoCAD

• Save the drawing as a DWG file
• Open this boundary in AutoCAD

The exact boundary of the site will open in AutoCAD up to scale. This helps you better understand the site limits and levels.

Step 3: Get the Heights Of the Site From Contour Generators

This step is more of a personal preference and does not have to be followed.

There are many site contour generators available on the internet. Enter your site coordinates and get the heights of the contours in your model. This helps in understanding the scale of the highs and lows in the site. 

• Once you open the contour generator on the internet, enter your site boundary coordinates 
• Press 'generate'
• An image with your site's height levels will appear
• Use it as a reference image for your model

Step 4: Draft Contours In AutoCAD

Once you understand the scale of the site and the contours involved, you can start drafting them.

• In the drawing of your site boundary, draw closed loops of lines representing the same height levels
• Take reference from both the Google Earth file and the contour generator
• You can draft each loop for a difference of 1 meter (or 5 meters, if the contour is very steep)
• Make sure that contour lines of different levels do not touch each other

To understand how contour lines work, click (here)

Step 5: Adjust The Line Elevations In AutoCAD 3D

• Once you are done with drafting the contour lines, click on each loop and go to the properties tab
• In the properties tab, you will find the elevation box
• Enter the value '0' for the lowest points in your drawing
• As you work your way up, keep increasing the value by 1 meter (or 5 meters, according to your scale) for the adjacent lines

Once you are done, you can check your drawing from a different 3D view to make sure all lines are properly elevated.

Step 6: Export the File To SketchUp

After finishing drafting in AutoCAD, export the drawing to SketchUp.

• Press 'file' and then 'export'
• Save the file
• Open SketchUp and under the 'file' tab click Import 
• Select the file you saved and click 'OK'

The drawing will open in SketchUp as a 3D drawing of your contour lines.

Step 7: Activate And Open The Sandbox Tool

In case you don't have the sandbox tool already, 

• In the windows tab, click 'preferences' and then 'extension'
• Click on the checkbox next to 'sandbox tools'

Doing this makes a set of tools appear on your SketchUp work window.

Step 8: Click The Tool For Creating Terrains

• Select the model you exported from AutoCAD. Make sure every line is selected
• From the set of sandbox tools, select the first tool, which creates terrains from selected edges
• Play around with the other sandbox tools to sculpt the contour to make it more accurate

Step 9: Smooth The Contour 

There is another plugin in SketchUp called JHS PowerBar

• Go to the extension warehouse and download the plugin
• Activate it in the extension manager tab

This extension has tools to smoothen, chamfer, and round surfaces.

• Select the contour surface you have modeled
• Click the second button in the set of tools that are present in the plugin. 
• Now the contour is more smooth

Step 10: Add Materials

Once the model is done, the last step is to add color and materials to it.

• Select the surfaces and go to the materials tab to choose appropriate materials for the model

Now that the model of the contoured site is done, you can now start designing your project by making use of it rather than leveling it. This is a more sustainable option for construction.