Week #12 – Site Survey and Topography Modeling
12-4. Advanced Site Creation: Level Dimensions, Regrading, Cut and Fill Calculations

ArchiCAD Training (Best Practices Lesson 12-4)

This 46 minute lesson starts with the creation of a quick site model with the Mesh tool, as in the introductory lesson of this module.

The external datum point reference elevation (Sea Level, in this case; but the principle applies to the Australian Height Datum AHD or other standard references) is set in the Options menu > Project Preferences > Levels and Project North based on its relationship to the elevation of the lowest story. Project Zero remains identical to the lowest story elevation, although it is possible to set it to another value if desired.

When creating the site mesh, it’s generally best to create it with the top height just below the lowest point of the site, and a minimal thickness (such as the default 3′ or 1m). Draw the mesh using only the main boundary points, and set the elevation of each one properly, then check in 3D to verify that the prevailing grade is correct and that you haven’t missed any of the points, and that they all have been set properly.

To minimize polygons (and thus the work by ArchiCAD to view or cut sections through the site mesh) you may want to create curved edges using straight segments. This is optional but may be particularly useful when a large or complex site is being modeled.

To create topographic contour lines, select the mesh and make sure the Mesh tool is active in the Toolbox. Click inside the mesh to start the contour, and keep clicking to define the topo line. You may terminate the line by double-clicking a point within the mesh, on its boundary, or outside the mesh (the line will get cut off at the intersection of the last line segment and the boundary). Press down on any of the points in that contour line, choose the Set Z-level option in the Pet Palette, and make sure to Apply to All so that all points in that group (the contour line that you just created) are set at the same height.

You may add individual grading points to the mesh without a contour line by starting the same way (with the mesh selected and the Mesh tool active, clicking inside the mesh) then clicking a second time on the individual point. After this point is created, you may press down on it and choose the Set Z-level option to set its height individually.

To annotate the site with Level Dimensions, make sure you activate the Gravity option in the Toolbar to Gravitate to Mesh. Click anywhere inside the mesh to place a dimension reference; if you click on a contour line you should get an exact value, whereas anywhere else you will get the interpolated value of the mesh surface.

The Level Dimensions will initially refer to the elevation as it relates to Project Zero. If you want to have these points refer to the external datum (such as Sea Level), you’ll need to select the actual Dimension Text element (not the bullseye marker for the dimension) and edit the displayed value to be Custom Text in the Info Box. Once you choose Custom Text, use the small popup menu to insert a reference to the desired datum point (clearing the original reference to Project Zero).

Unfortunately, there is no way to set the Level Dimensions to default to displaying Sea Level or external datum references, so one has to “fix” this after placing the dimension elements. To do this quickly, select all Level Dimensions, then Shift-click to select ONE of the Level Dimension Text elements, and make the adjustment as above. All of the selected Level Dimensions will have their Text elements affected.

To regrade a site, one may create a copy of the original mesh and put it on a separate layer. You may then move contour lines around or add additional contours or individual point references. You may also use Solid Element Operations (SEO) to clear a space for the building slab and foundations (use Subtraction with Upward Extrusion to remove the volume of the slab plus all the air space above it).

It is easy to calculate cut and fill volumes by using SEO between the original and new mesh elements. As a starting point reference, the original volume of the terrain may be viewed using the Window menu > Palettes > Element Information palette.

To calculate the volume of material that needs to be Cut from the original terrain, simply use SEO to subtract the new mesh from the original mesh. To get the Fill volume, use SEO to subtract the original mesh from the new one. In either case, the modified elements may be viewed in 3D to see the volumes cut or filled. It may be desirable to set the materials for each mesh to different colors for clarity of presentation.

To retain the Cut or Fill volume element for reference or inclusion in an Interactive Schedule, a series of four separate Mesh elements is required: one for the original terrain, one for the final terrain, and one extra copy of each that is used with SEO to model and calculate either the Fill or the Cut volumes.

Please post your comments and questions below.


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ArchiCAD Training: Advanced Site Creation: Level Dimensions, Regrading, Cut and Fill Calculations

Let us know how you feel... (12 comments so far)

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  1. GeneGillespie
    12 years ago

    This is a great Lesson, but I cannot get the Mesh and Model to work together. Even tried Youtube lesson and got similar results. Problem, as in Youtube exercise:
    a. Set Proj. Pref
    Project Zero — 0
    Sea Level ————— -71′
    b. Walls of Bldg. to Current Story, 1st Fl — 0
    to Sea Level ——————- 71′
    c. Mesh settings thickness ————- 3′
    to current story — -11′
    bottom of Mesh set at 60′
    When I select all and show in 3D, the bldg is always embedded 61′ below the surface of MESH,
    but these are the same setting as shown in your video. Can you help me?

    • Eric Bobrow
      12 years ago

      Gene –

      You write that the mesh is 3′ thick, but then mention that the building is embedded 61′ below the surface of the mesh. Is the mesh actually a thin piece (3′ thick) or is it 60′ thick?

      If it’s not a thin sliver to begin with (before you adjust the height values for the boundary points) then you may have inadvertently set the thickness to 60′ instead of the elevation to Sea Level.

      When you first start out with the mesh, create the basic shape with the parameters set for the thin base, and look in 3D to check that everything is looking OK – that the building is floating above the mesh the correct amount. Then, adjust some of the outline boundary elevations, and make sure that you are entering the height values with the popup menu set to Sea Level references, rather than in relation to the base of the mesh. Check this after you’ve done a few points to make sure it is working properly, then proceed.

      Let us know if you are now able to figure this out. I think it’s probably one little setting that’s throwing you off, either in the initial setup of the mesh (that thin base) or when you’re inputting the elevation values (referring to the mesh base rather than Seal Level – which is probably what you should be using).


    • GeneGillespie
      12 years ago

      Thank you for that, I completely missed that it needed to be set to Sea Level.

      • Eric Bobrow
        12 years ago

        Gene –
        Glad you were able to track down the one missing step!

  2. GeneGillespie
    12 years ago

    I have created the Mesh multiple times, trying to get exactly the same settings and my Mesh always shows up as 895′ feet deep or tall, not shallow like yours. What am I missing?

    • Eric Bobrow
      12 years ago

      Gene –

      Open up the Mesh tool settings before you place the Mesh or with the Mesh selected.

      In the Mesh Default (or Selection) Settings, you’ll see three numbers in the upper left area. The first (top) number is the thickness. This should be set to a small value to give a shallow base to build on top of. I think this must be where you are inputting the 895′, and it should instead be set to 10′ or a small value.

      The second and third fields are linked, and by default will reference the elevation for the mesh to the Current Story and to Project Zero. You may change these to refer to Sea Level or AHD or whatever reference you find most useful. This elevation in general should be set to a height just below the lowest elevation for your site. That way the mesh will be thin at the lowest point, and be as thick as necessary for the rest of your site.


  3. Graham Hobbs
    12 years ago

    At 25:35 you show selecting all the Level Dims then shift clicking to select the level text. No matter how many ways I try to do the same, the Info Box stay on the Level Dim settings and does not change to the Text settings. I can get the Text settings OK for an individual level and set the custom height as shown. But not when selecting all the Level Dims in the method that you show.
    What I was able to do with all Level Dims selected was this: I right clicked over the a Text handle on one of the Level Dims and then I got the Text Info Box and I could then set the Custom text, however this effected only the one Level marker and none of the others.

    • Eric Bobrow
      12 years ago

      NOTE TO COURSE MEMBERS – Graham Hobbs and I had an extensive email exchange on this topic. I am posting Graham’s slightly different method that he found to work on his computer, along with my own summary of steps that work for me.


      By trial and error I have found a method that works on my ArchiCAD to multiple change the Level Dim Text Settings.

      Starts the same:
      · Level Dim tool selected
      · Select All Level Dims
      · Shift Left click the handle of one of the Dims text boxes and the box shows as selected

      · Keeping the shift key down, and the mouse still over the text box, right click for the contents menu, which shows at the top “Dimension Text Settings”
      · Move the mouse and left click to select “Dimension Text Settings”
      · This opens the settings box and can change to AHD/Sea Level and all Dim Text are changed.

      My steps can be summarized in the following way:

      · Level Dim tool selected
      · Select All Level Dims
      · The Info Box shows Level Dims icon

      · Shift Left click the handle of one of the Dims text boxes and this text box shows as selected
      ** The Info Box then switches to show the Text Tool icon, indicating it is the Last Selected Element

      · In the Info Box, either click on the Text Tool icon and open up the Settings dialog, where you’ll see the Dimension Text Settings available for setting – change from Measured Value to Custom Text, and adjust as desired using Insert Autotext popup menu and field text editing area

      — or —

      · Simply make the change in the Info Box directly from Measured Value to Custom Text and adjust as desired (similar to above)


  4. Avatar photo
    12 years ago

    Re-selecting an individual level dimension with them all selected to customize the text is something I would never have figured out! I don’t have ArchiCad handy but I’m assuming you can also change the format of the numbers of the level dimensions from feet and inches to decimal feet. Is this correct?

    • Eric Bobrow
      12 years ago

      John –

      Yes, you can change the format of the numbers of the level dimensions to decimal feet. The control for this is in the Options menu > Project Preferences > Dimensions dialog box. You’ll see the control for the Level Dimension format as the fourth from the left.

      You may either change this setting for the Dimension Preference that you use all the time (one of the named presets in this dialog) or create a new Dimension Preference for use on specific drawings. Since the Dimension Preference is one of the items recorded in the View Settings, this will ensure that whenever your View is activated (as you are designing, or in a Drawing placed on a Layout) that the Level Dimensions are in the format you need.


  5. Avatar photo
    12 years ago

    Some great tips here. The use of the Level Dimension tool was a good one, with the “gravity” set to slab, and the option to customize the text to sea level. Getting element information to identify mesh volumes was another that I didn’t know about – thanks for the good advice on both of these!

  6. AntonioTort
    12 years ago

    Hi Bob!. You’ve explained the core of site modelling with really understandable words. Specially the final part of adding and substracting land volumes. You changed one of my ArchiCAD’s beasts into a friendly pet! Great job!