ArchiCAD Basic Training – Module 7
7-2. Site Modeling with Mesh, Slab and Object Tools

ArchiCAD Training –  (Quick Start Course – 7-2)

This 49 minute lesson offers an explanation and demonstration of creating a site model using the mesh (terrain), slab (hardscape) and object (trees etc.) tools. A prepared survey file is brought in as a DWG and placed as a reference underneath the building to use as base for tracing the site boundaries and recreating the topographic contour lines.

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Two versions of the DWG are available here on this page for following along with the video, one in imperial (feet) and the other in metric. An independent Worksheet is created for placing the DWG into the file; in versions of ArchiCAD that do not have worksheets, an independent Detail window may be used, or in version 10, an extra “dummy” story may be created so that the “ghost story” option provides a tracing image similar to Virtual Trace.

Ideally, the scale of the Worksheet (etc.) should be set to the intended printing scale (e.g. 1/8″ = 1′-0″ or 1″=20′-0″ or 1:100 etc.) of the site plan before importing the DWG so that the text appears correctly in relation to the site geometry. The File menu > External Content > Place External Drawing command is used to import the DWG. (In the Start Edition one may use the File menu > File Special > Merge command instead; the effect is different, but for this lesson it will work just fine.)

While placing the DWG, the Drawing Unit dialog offers the opportunity to confirm the size of the internal DWG measurement unit, which will generally be Feet in the U.S. and may be Meters or Millimeters in international usage.

After importing the survey, it is important to verify that a known distance from the drawing matches the distance displayed by the Measure Tool. If it does not, then the simplest way to correct this is to calculate the proportion difference (e.g. the size is 12 times or 10 times too big or too small, etc.) then Undo, and reimport using a different measurement unit. Repeat if necessary until the survey dimensions are verified as accurate.

On the ground floor, a new View is created with the Site layer combination. (Note that the Quick Options palette makes it easy to change layer combinations on the fly.) If necessary (as demonstrated in the international project file) it may be useful to adjust the Site layer combination to include the exterior walls of the building; remember to Update the layer combination after making the change so it is recorded properly.

The survey worksheet is set up as a Trace Reference, then with the Drag Reference command (using the button in the second row, second from the left, in the Trace and Reference palette) the survey image is repositioned to coordinate properly with the building.

The relationship of the current Project Zero – often this is set as the top of the finish floor of the main story – to Sea Level or a standard height datum – is set in the Options menu > Project Preferences > Levels and Project North (or a similar command; this varies in different versions of ArchiCAD). The Sea Level or Reference Level is set to the appropriate offset from the Project Zero so that when the terrain is created it is easy to input and reference grading elevations based on the external datum value.

The Mesh Settings elevation is then set up to reference the Sea Level or Height Datum rather than the Current Story or Project Zero. An initial base is created by tracing the outline of the site boundary, snapping carefully to each node point. After the mesh is in place, it is viewed in 3D – it is a flat slab, floating a bit below the building.

To edit the details of the mesh height values, it is important that the mesh tool be active in the Toolbox, and the mesh be selected. Each node point is clicked on, and using the pet palette Z-height option, set to the appropriate height above Sea Level or the Height Datum. Do not click the Apply to All checkbox when changing the Z-height; do each one of these nodes one by one. The mesh is viewed in 3D again, and now the prevailing grade is clearly visible, and the building is partially enveloped by the terrain.

Before creating each topographic contour,  add new node points where that contour line meets the site boundary, then set the height of each node properly. This sets the exterior of the mesh to a more precise representation of the grade.

To create a contour line, click slightly inside the mesh perimeter, then click a series of points to roughly trace the topographic line. Click twice on the last point to finish, and accept the default choice (“match to existing contours) in the Add Points confirmation dialog box. After creating the contour line, with the mesh still selected, press down on any of the interior points of that polyline, and use the Z-height option in the pet palette to set the height of all of the points in that polyline (click the checkbox “Apply to All”).

Repeat the process for additional contour lines as needed, and know that you can add more at any time. Do not overdo it, and don’t put too many node points while tracing – this will add needless polygons (detail) to your model that may slow down the responsiveness as you view and work in 3D.

The mesh element may be set to display all contour lines on the plan, which can get messy as more contours are drawn and ArchiCAD calculates all the triangular surfaces necessary to represent the geometry. To turn this off, use the option in the Floor Plan and Section panel or popup > Outlines to Show User Defined Ridges rather than Show All Ridges. A similar option exists for the 3D model representation, which you may adjust in the Info Box or the Mesh Settings: choose All Ridges Smooth in the Model panel.

When viewing the Sections of the building, use the Design menu > [Connect submenu – in ArchiCAD 15] > Solid Element Operations (SEO) command to carve out the floors from the terrain mesh. Select the floor slab and make it the Operator, select the terrain mesh as the Target, and use the Subtraction with Upward Extrusion command – voilà – the terrain is cut to make way for the floor and walls above.

To add hardscape such as a patio, use the slab tool and set the elevation properly, perhaps by eye-dropping an actual floor slab. If it is buried in the terrain, use the SEO palette to carve out the slab from the terrain. This may be done from the plan view, since it is easy to select each of the elements.

The slab hardscape may be set to a different material, perhaps a concrete or stonework. If you’d like to see a hatch pattern on the plan, you may activate the Floor Plan and Section > Cover Fill option, and either use the Fill that is associated with the material, or set it to an independently selected Fill.

Finally, the object tool is opened and tree objects are located using the Find by Keyword option. To place the trees at the right elevations in relation to the terrain, the Gravity option is turned on, and the sub-option selected to Gravitate to Mesh (rather than Slab, Roof or Shell). Then when the tree object is placed, either on plan or in 3D, it will pick up the height of the underlying mesh and use that as the base height for placement.


  • In the final segment of the lesson, the first operations are repeated with the International metric survey to explain a few differences in the setup of the International template and project file. The 01 Site layer combination is enabled, but it does not show the exterior walls; this layer combo is updated to turn on the Structural – Bearing layer, on which the exterior walls are placed. In addition, the mesh tool is set by default to show a Cover Fill; this option is turned off to make it easier to see the working area.
  • If you’d like to see the terrain mesh in your Section drawings, one other change will be necessary in the international version. The clone folder for Sections uses the 04 Plans – Approval layer combination, which does not show the Site & Landscape – Terrain layer. I suggest creating a new layer combination for Sections (in the Layer Settings dialog, activate 04 Plans, and then click the New button in the bottom left to create a new layer combination with identical settings). In that Layer Combination, turn on the Site & Landscape – Terrain layer, and click the Update button to record the change, and click OK. Then highlight the Sections clone folder in the View Map, click on the Settings button, and adjust the Layer Combination to use the one for Sections that you just created.
  • When placing the trees, a good layer combination to use for the international file would be 08 Rendering, since that turns on the Site & Landscape – General layer.

Your Downloads

You may need to right-click the following links and select Save Link As to download the file to your computer. Remember to unzip the file before trying to place the DWG into your ArchiCAD project.

Your Downloads

You may need to right-click the following links and select Save Link As to download the file to your computer

Click here to see the transcript of this ArchiCAD training lesson...

ArchiCAD Training: Site Modeling with Mesh, Slab and Object Tools

Let us know how you feel... (15 comments so far)

The comments are closed.

  1. PamelaGoode
    12 years ago

    Thanks Eric for this video. I have a question for the opposite building to mesh relationship. I am trying to draw a retaining wall where the wall needs to extend down to the mesh on a steep sloped site. Similar to how the Roof/wall tool attaches the wall to the roof and extends the wall up to a gable roof. Can I extend walls down to the mesh? Or is there a way to draw the wall using the gravitate feature. The grade is sloping so the wall will need to slope at the bottom. Does this make sense? It is hard to explain.

    • Eric Bobrow
      12 years ago

      Pam –

      You may simply draw the wall with a fixed base elevation and height, then trim off the bottom to meet the grade by using the Subtraction with DOWNWARD Extrusion (instead of Upward). This will trim off the bottom of the wall as it meets the grade.

      Three additional notes:

      1) There is no way to automatically “extend” the walls down to the mesh. You’ll need to draw them at an appropriate elevation so that they already are in the right place; you can also grab the bottom in 3D or in a section or elevation and use the Pet Palette to adjust the bottom down as needed.

      2) If the retaining walls are not actually built above grade (i.e. if they are buried in the ground for structural stability) then you will want to follow the standard instructions in the video to place their base elevation under the grade level, and subtract out these walls from the mesh. If on the other hand, they are built totally above grade (perhaps a simple way to model a temporary fence) then you can use the method described in this note.

      3) You may use the Gravitate feature to set the base height of a wall (just as you can for trees or other objects); it will set a uniform base using the point elevation of the mesh at the click-point. The base of the wall will not slope, unless you use the SEO method after the wall is drawn.


      • PamelaGoode
        12 years ago

        Thanks for your reply. The wall is above grade and sloped on the top. I assume I use the SEO to create the slope on the top of the wall, but what do I use as the operator. I tried a line at the right slope, but it did not work. I assume I need a plan or 3D object that slopes in order to angle the top of the wall. How do I do this?

        • Eric Bobrow
          12 years ago

          Hi Pam –
          To slant the top of a wall in ArchiCAD you may use an SEO with a roof or an angled beam; if these elements are not actually going to be seen in the finished model, then you need to put them on a different layer, and hide that later. This is commonly done in ArchiCAD – a single layer reserved for “SEO cutting elements” may be used for all similar elements. This layer is turned off at all times except during the actual modeling.

  2. Isabella
    12 years ago

    Hello, my name is Isabella, I am Brazilian and architecture student. I just LOVE your tutorials … They help me a lot. Agredeço much for you to have your time trying to transfer knowledge to other people!
    My Congratulations, very successful and that God enlighten!
    Kisses from Brazil and mine.

  3. KennethMunson
    12 years ago

    Hi Eric,

    I am working on getting up-to-speed with ArchiCAD via your QuickStart Course and Best Practices Tutorials. Thank you again for undertaking this task. I cannot understand why Graphisoft has neglected this manner of educating it’s users as it is fundamental to fully understanding how to use their program. Good for you to take the lead!

    To that end, I purchased your MasterTemplate and Best Practices Tutorials. My thought is that they will provide me with a “better” starting point than the “vanilla/out of the box” ArchiCAD. To most effectively learn ArchiCAD;
    1. When should I “bring-in” your MasterTemplate to my learning environment?
    a. With the QuickStart Course tutorials?
    b. With the Best Practices tutorials? (Will the BP be similar to the QuickStart Course material, and be a model/project that we continue to build/improve with more complex detail?
    c. Wait to import/implement the MasterTemplate with a first project? (I assume that there is a tutorial for MasterTemplate?)

    As I am a sole practitioner and do not have anyone available to turn to in the office for questions/hint’s/support, so I need to learn the program as efficiently as possible. To that end, I find the video tutorial most effective. I utilize two display monitors, side-by-side, one showing your tutorial, the other, my work-in-progress. I start & stop the video making sure that all of my actions/setting match yours. If something is not working, I can usually see the error by comparing both screens/displays and their work environments.

    My “plan” is to go back through the QuickStart Tutorial and draft/draw/model another simple house on a hillside. With this approach, I will review all of the information presented in the QuickStart Tutorials/Lessons. Would this be a good place to start/use the MasterTemplate? Is there a better place to start learning MasterTamplate? Start with the Best Practices Course material?

    Your suggestion(s) are much appreciated?

    Kind Regards,

  4. RodneyDay
    12 years ago

    Hi Eric,
    I can’t seem to locate the pdf file you are using in your tutorial.. Am I not looking in the right spot?

  5. TomislavNirt
    13 years ago

    Hi Mr.Eric,I am totaly beginner in archicad and already I was learning more things and help on that.
    Now i am interesting in this video I cant export house Smith only terrain-did i something doing wrong or somewhere is download link for project.
    P.S.Sorry on bad english i am from Croatia.

    • Eric Bobrow
      13 years ago

      Tomislav –

      Thank you for posting your question.

      I’m not sure I understand what you’re saying. You don’t need to export the house in order to work on the terrain. You will simply import the DWG file (supplied as a download, above) into a Worksheet into the project file (which has been built up during the course by students).

      Unfortunately, it’s not practical for me to provide a download link for the project file itself, since students who watch these lessons may be using different versions of ArchiCAD. In order to share the project file, I would have to create one in every different edition since ArchiCAD 10 (i.e. AC10 USA, AC10 INT, AC11 USA, AC11 INT, AC12 USA… etc.). This is why I rely on students going through the course to build up their own project file to use during this lesson.

      You can apply these principles to working on the terrain in a blank project, just skipping over the steps that involve Solid Element Operations for the building. You can also adapt the lesson to work with any building, which is of course the point of learning – you will eventually apply these same techniques to your own projects.


  6. MichioValian
    13 years ago

    Hi Eric,
    Quick question regarding this lesson. The scale of the survey was set to 1/8″. When the model, in plan view, was placed with the survey, the scale of the model was at 1/4″. Was this deliberate?

  7. Avatar photo
    13 years ago

    Eric, is there an easy way to use existing contours from a surveyor’s DWG file rather than tracing a PDF? On more complicated sites tracing contours could be very time consuming. I seem to remember using DWGs in the distant past but have forgotten how. [It’s also possible that it was with another CAD program too! 🙂 ]

    • Eric
      13 years ago

      John –

      In this lesson, I did bring in a DWG file, then manually traced the contour lines. The same process can work perfectly well for PDF versions; you will need to make sure it is imported to proper measurement scale, and you will not be able to snap to the linework, but may zoom in and get close enough for most purposes.

      If your surveyor has created a 3D model file, rather than just linework, then it may be possible to import it as an object using the File menu > Libraries and Objects > Open Object command. However, in my experience, many times these 3D files actually just have the contour polylines set at the appropriate heights, but do not have an actual surface, let alone a solid volume, created as a “model”.

      In addition, there are often issues with working with the original linework and/or model without reinterpretation by you as a designer. For example, you can use the magic wand to automatically trace polylines from a DWG survey, but often these have LOTS of points or segments and cause the mesh to have WAY too many polygons for comfortable use.

      In practice, I find that manually tracing the polylines gives the designer the control to follow closely where it needs to be as accurate as possible (for example, in the immediate neighborhood of the building) and less closely in other areas where it is mainly used for context. In fact, it is not generally a good idea to trace every contour line, since doing so adds much more “weight” in terms of complexity / polygons, without adding much to the realism or usability of the terrain model.

      So this doesn’t have to be very time consuming – you just have to know how much detail you want to create, and only put that in. If you need more detail later, you can always add it.


  8. Avatar photo
    13 years ago

    Hi Eric,

    This video covered a topic I had very little experience with but have been trying to learn on my own, with fairly decent results. After watching this video however, I feel like I’m learning how to do it for the first time. No more fumbling.

    Thanks as usual for making the seemingly difficult – simple.


  9. Albert Van Ee
    13 years ago

    Thanks again for a clear and concise instructional video. I often get the terrain model sent in PDF form and have great difficulty sizing it properly. Any suggestion would be welcome. Thanks again

    • Eric
      13 years ago

      Albert –

      Thanks for your positive feedback on the video.

      Just like DWG files, it’s best to set up your scale in the Worksheet to match the intended printing scale of the PDF before you place it. When you place the PDF at 100%, it will often come in exactly the right size.

      If this doesn’t work properly, you can scale it by trial and error, fairly quickly and precisely by adjusting the scale percentage numerically in the Drawing Settings dialog. Draw a line in ArchiCAD of a known size or distance that should match something from the survey PDF, and then tweak the size of the PDF to match. After a few tries, you should be able to get it to match as closely as desired.