> For the complete documentation index, see [llms.txt](https://windows.help.formit.autodesk.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://windows.help.formit.autodesk.com/formit-primer/part-ii/2.4-3d-terrain-workflows.md).

# 2.4 - 3D Terrain Workflows

*In this chapter we are going to explore working with the 3D terrain, making use of multiple tools covered in previous chapters. Using a site with steep topography, we will take the terrain that gets automatically imported, prepare the geometry, and then cut a hole for a basement from it.*

*If you wish to use exactly the same location as demoed in this tutorial, open the* ***2.4 – 3D Terrain Workflow\_Start.axm*** *from the* ***FormIt Primer Part 2 Dataset**.*

1 – Start a new FormIt file, and import the 3D Terrain using the **Location (SL)** tool. Use the address “**120 Arapahoe Ave, Boulder, CO 80302”**, and select a region to import similar to the image below, making sure to include the octagon-shaped building. (If you are starting from the ***2.4 – 3D Terrain Workflow\_Start.axm*** file you can skip this step.)

![](/files/-MlG7ufBaKaeYZS7UVZG)

***Note:*** *For more information on how to use the set* ***Location (SL)*** *tool, refer to the **Part I** chapter **1.1 – Set the Location**.*

2 - In the **Layers Palette**, turn on **Terrain** layer, which was automatically created when the Terrain was imported.

![](/files/LZ9s4DdNYoLDI1LE2DgM)

3 – The 3D terrain is imported as a mesh object, but before modifying it, the terrain must be converted to a FormIt geometry Object. This can be done using the **Meshes to Objects (MO)** tool:

1. Edit the **Terrain** group, and select all of the faces in that group.
2. Right-click one any of the selected faces to bring up the Context Menu.
3. Select the **Mesh To Object (MO)** tool. The mesh will be automatically converted to a FormIt object.
4. Finish editing the group.

***Note:*** *What is a mesh? In short,* ***Meshes*** *are lightweight representations of geometry, but* ***Objects*** *are more editable. To learn more, see the* ***Meshes*** *chapter in the* ***Tool Library**.*

![](/files/-MlG7ufFqpK5AvEpDcmB)

4 – The next step is to create a second object which we will use the cut the Terrain. For this example, we will create an octagon based on an existing building in the site.

1. Turn off the **Terrain** layer.
2. Draw a **Polygon (Y)** with **8** sides and a **30’** radius, and place it on the **XY Plane.**
3. From the **Top View (VT)**, move the octagon so that it is directly over the similarly-shaped building visible in the satellite image.
4. Move the octagon up vertically **150’** along the blue axis (**Z Axis**).
5. Turn the **Terrain** layer back on.

![](/files/-MlG7ufHxDhK1UAzBr5i)

5 – Next, we will cut into the Terrain. For more information on how to use cut, and other advanced modeling tools, see chapter **2.2 - Advanced Modeling Tools**.

1. Extrude face downwards, so that it dips a few feet beyond the top face of the **Terrain** group.
2. Use the **Cut Geometry (CG)** tool to carve the extrusion out of the **Terrain**.
3. Delete the octagon we just used to cut the terrain. You should be left with just an octagon-shaped hole.

![](/files/-MlG7ufIRu3sfGKFDwgZ)

6 – Extrude the cut bottom face to adjust the basement depth. In this example, we aligned the base to the lowest point in the site.

![](/files/-MlG7ufJVPK4PZG3tS0q)

7 – To experiment with a few more FormIt features, you can continue manipulating the terrain in the following way:

1. Use the **Extrusion Tool** once again, to readjust the base depth to be about midway between the highest and lowest point of the octagon.
2. Created a new material and applied it to the unpainted faces.
3. Use the **Tilt Face (TF)** tool to create a softer transition between the base grade and the natural terrain. Now we have a nice platform to build our octagonal building on, based of the real terrain data of the site!

***Note:*** *To learn more about the* ***Tilt Face (TF)*** *tool, see chapter* ***2.2 - Advanced Modeling Tools**.*

![](/files/-MlG7ufLRnWmA6DewdcI)

***Note:*** *To compare your results to ours, check out the* ***2.4 – 3D Terrain Workflow\_Completed.axm*** *file from the* ***Encode Model Data Set**.*