Creating a clean drawing from a 3D Model in Rhino


Demon 1004.jpg

This workflow details methods for the creation of a section and plan drawing from a 3 dimensional model in Rhino and the process for cleaning up the output, deciding what information to keep / delete and what needs to be drawn to complete the understanding of the space.
Uses Tool(s) Rhinoceros

For your presentations, you will not be able to rely on other drawings, screenshots in your sketchbook, or laptops with your 3d model open, in order to discuss the project. Therefore, you must distill the various alignments, manipulations, rotations, and originating moves that went into your 3d model back to a 2-dimensional representation. Architects must do this at every step in their process.

Please use the digital model to follow the workflow

Sample file

Create Section drawing

Save + Copy the Original Digital Model

Before starting the workflow, be sure to save the Rhino file as a separate copy so as not to lose work of the original, complete digital model. When creating drawings, there is potential for some of the model to be trimmed or deleted, so it is important to keep a copy of the original for other drawings. Step 1 copy.png
For the purposes of this workflow, you can also copy the digital model twice in the same file: one for the section drawing, one for the plan. In the Front view, select the entire model and Copy it to the right. Select the copied digital model in its entirety and Hide it. Later, we can Show this model when moving onto the plan drawing.

Prepping the Digital Model

When making a section or plan drawing, it is important to "clean up" the digital model so that unnecessary linework or surfaces are removed before cutting, splitting and flatting the model. For example, the digital model may include numerous construction lines that were helpful when creating the model that should now be removed or hidden in order to not get in the way of the clean surfaces. Step 2 clean up.png Use the command SelCrv to select all the existing curves in the model and then put them on a separate layer titled "Construction Lines". This way you can refer back to them at a later time, if needed. Turn this layer off.

Producing the Section Cut

Step 4 new layer.png First, create a new layer called “Section Cut”. Make that layer the CURRENT layer by double clicking on it. Then make sure all of the objects you want to cut through are on unlocked layers.

The section line should cut through an important moment in your design. Start on one edge of the ground-object and then snap to the perpendicular point on the opposite edge of the ground-object. In topview, type “Polyline” and draw a line longer than your box in the direction you want a section. Make sure you have checked the box for the perpendicular (Perp) OSNAP. Then choose a line which runs across the site, which *must* cut through the building. Select the entire digital model and use the command CutPlane to create the section plane. Use the line you just created as a reference through the building. You can always select the plane and type Move to move the plane to your preferred section cut. Your model should look something like this: Step 3 cutplane.png Make sure the plane fully intersects the polysurface on all sides. Next we will make the section lines. Select all the surfaces of the digital model. Use the command Section and click one corner of the plane, then click the opposite (diagonal) corner of the plane. The section should be highlighted. Move it to the Section layer if it is not already there. Press space bar to end the Section command. Preview the section linework by looking at the Front view.

Splitting the Model

The next step involves hiding half of the building section that is facing the other direction of the cut. First we need to split the entire model along this cut plane. Select the entire model and type the command Split . Select the CutPlane as the cutting object. This command may take some time because it is testing every surface within the model against the cut plane (which is why it may read in the command box "Split failed" for every surfae that is not actually crossing the plane). It might as well as turn your model back to wireframe to alleviate the process. Step 5 split.png Once finished, move to the Right view and select all of the surfaces that are left of the CutPlane. You can select these easily by making a cursor box from the bottom right to the top left. Once these are all selected, Hide them so they are no longer in view. Step 5 split hide.png Note: If your SPLIT fails, you might need to Explode some polysurfaces or Ungroup objects. Choose the correct view (in this case, the Front view) which looks through the open end of the section cut. Next, you will make a 2d line drawing of this cut.

Cap the Cutting Edge

When looking at the plan view of the model ( the Top view), the model looks almost ready for flattening. However, when splitting the digitial model including the walls, floors and other closed polysurfaces, the sectioned model now looking into these empty spaces. To cap these"openings", we can use the Section command to generate the edge curves along the cutplane. After finishing the section command process, before deselecting these curves, we turn off the cutplane layer and use the PlanarSrf command to create the cap for the model.

When we are processing the PlanarSrf command, the option box might pup out, just click OK .

Planarsrf option box.png


Use the Make2d command to produce the 2d section linework. Be sure that you are in the viewport looking directly at the open cut of the section you made in the previous step (once again, the Front view for this example). Start the Make2d command, select the objects and press enter.

Step 7 make2D.png

For the 2d Drawing Options, choose Current View under Drawing layout. Check Maintain source layers, every layer will be maintained with a separate layer for Annotated, Hidden and Visible linework. Press Okay.

Your drawing has 80% work to do after Make2D You still need to:

Clean up lineworks
Reorganize Linework Layers
Adding Detail Elements
Align Drawings

Clean up lineworks

You now have the linework of the previous view, located near the origin in the Top view. All of the linework is flattened according to the layer organization of the surfaces. Remove unnecessary layers by using the Purge command. This will remove every layer that contains no linework (such as all the unnecessary "Annotation" layers).

Use offset to create material thickness, such as walls, glass panels.

Use Delete , trim , split , extend , joint to clean unwanted lines.

Reorganize Linework Layers

At this point, you will want to create layers for the different line weights and assign the lines to their respective layers. Create layers for lineweights: Cut line, heavy, medium, thin, tiny, dashed. Reassign the curves to the appropriate layer. Clean-up the linework as necessary. Step 7 organizing.png

For example, hide all the layers except for "Section Cut - Visible". Trim the areas where there are unecessary lines (such as corners, overlapping boundary liens, etc). Move all of the Wall section lines to the heaviest layer "Cut line". Move the thin window section lines to a medium layer.

Adding Detail Elements

At this point, you should add detail elements that are accurate for the scale of your drawing. Now is also the time to accurately draw mullions, stairs, ramps, materials and any overhead information (these elements are generally not found in make 2D exports). At the very least you will likely want to change some wall thicknesses at this stage to better describe the different material conditions.

Create Plan drawing

Next we will applied similar workflow to produce plan drawing. The only difference is the orientation of the cutplane, we need to create the cut plane from the Top view.

Prepare the Plan Cut

Be sure to move the linework you have created in the previous step so that new linework is not placed on top of it when you use the Make2d command again. Follow Steps 2-10 but with slight alterations taking into consideration the notes below.

Use the command Show to show the duplicate model that was hidden in the first step. Hide the previous section model so as not to confuse you later on. Make the new section plane by creating a Line in the Front view that extend through the lenght of the building. Plans are always drawn with the section cut 3' above the floor, therefor this plane should be located 3' above the floor. Move it into place. Use the CutPlane to create the CutPlane.
In the Section layer, use the Section command and preview the plan in the Top view. Split the model using the CutPlane made in the previous step. Hide the top half of the building by selecting the split surfaces in the Right or Front view. (You will return to these hidden surfaces to create the Above linework later.) Move the section linework plus trimmed cut plane above the model in the Front or Right view so that no linework is missing in the final Make2d.

Plan make2D before.png Make2d the sectioned model in the Top viewport and clean-up / reorganize the linework as necessary.

Plan make2D after.png

Plan Vs. Section : What's different?

Aside from cutting the digital model in different directions (horizontal versus vertical), the process between making a plan drawing and a section drawing is very similar. Here are some of the added steps for plan drawing:


Detail difference.png Some of the details added to the plan are different from the section, for example, stairs and door swings need to be revised according to convention. In this case, we might want to redraw the sliding door so that it looks like it's opening. Add an arrow to show which direction it slides towards.

Above (Dashed) linework

Dashed lines represent hidden linework, often what is behind the section cut. In section drawings, this is often rare to include, however in plans - it is important to represent what is above the plan such as overhangs, openings or changes in the room height. To do this, return to the digital model and Show the surfaces that were hidden after splitting. Use the Make2d command to draw the linework that represent the above roof that overhangs. You can also select additional surfaces to help reference where the roof is in the plan drawing. For this example, select a wall. After you Make2d these elements, place them in the cleaned up plan drawing and trim out additional, overlapping lines. This new linework should be located in a new layer titled "Above - Dashed."

Create Elevation drawing

When making elevation drawings, we don't need to create cutplane. We Make2D from either right view or front view.

Elevation make2D.png

Elevation screen shots.png

Align Drawings

Before exporting, set up the plan and section drawing so that they reference each other. This way, the viewer can easily understand where the section is cut and how the two drawings work together.
To do this, create a construction line using the Polyline command in a layer for light linework that runs perfectly straight along the y-axis in the top view. Attach this line along one edge of the section. Copy this line along another edge of the section, such as the opposite wall. Then, Move the plan drawing so that it fits in the same framework as the section. See example above. Make2d-19.png You can also add a section line marker in the light layer (notice how this layer is being used for both notations and light details in the drawings) by drawing a perpendicular line across the plan in the location where the section Cut Plan was located in the digital model. Refer back to the model to place the line. Add side markers (such as arrows or simple lines) to show which direction the section is looking.

Text can be added later in Illustrator.

Exporting to Illustrator

Make sure you are in topview. Select all of the drawings, including the light notations made in the last step, and use the Export command to save it as an Illustrator file (.ai extension). The next prompt selects scale. You need to export your linework to the scale you want (1/8” = 1’, 1/2” = 1’, etc.). Whatever scale you export in will be the scale your drawing opens up at in illustrator. Scaling in Illustrator is imprecise. In this case, we want to save it as a 1' = 1/4" drawing, so type "1 foot = 0.25 inches" in this command.

Adjust linework in Illustrator

Once in Illustrator, re-position the drawing into an artboard that fits. In this case, adjust the artboard to a size of 24" x 26" and move the linework to the center of the page.

All of the linework should be adjusted to a black line with different stroke weights. In this instance, the strokes were changed to the following weights:

  • Section - Heavy = 1.2 pt
  • Medium = .5 pt
  • Light = .25
  • Extra Light = .125
  • Above Dashed = .25 (This should also be made into dashed linework with a spacing of 3 pt, 3 pt.)


Majority of the time working on your drawings will probably be spent cleaning up the Make2d output and assigning lineweights. These lineweights are crucial in helping your drawings read properly. Notice the differences in the drawings below: Lineweight Example.jpg

Use your experience from past projects to coordinate lineweights, especially regarding what lines were too thick (no thicker than 2 pt), what lines were too light and didn't show up (less than .12 pt will not print) and what hierarchy helped your drawing read properly. Refer to the lineweight distribution below for reference:

Common Mistakes + Problems

Messy Dashed Linework
It is rare to use different dashed lines to represent different "above" elements. The above elements are often simplified to an overall boundary line to show the roof overhang and important elements within the room such as a skylight or protruding mezzanine.

No Thickness
If your digital model uses only single surfaces for the walls, floors and ceilings, then you must edit your drawing to incorporate some sense of thickness for these elements - as it is impossible for a wall to be a single surface. Floors especially should have a thickness to represent the structural weight that makes up a floor. Wall thickness may vary dependent up on the material. Judge accordingly.

Untrimmed Corners
Making the model have thickness can involve creating numerous surfaces that have overlapping corners which can be easily visible in the Make2d linework. It is imperative to trim and clean the section linework so that it reads clearly.


These books are helpful references for drawing standards:

Details in Contemporary Architecture , edited by Christine Killory and Rene Davids
Good examples of wall sections and details by contemporary architects
Details in Architecture , edited by Andrew Hall
Clear examples of assembly systems tied to key works with good diagrams
Architecture in Detail , by Graham Bizley
Good color coded section axonometrics with clear material information
Building Construction Illustrated , by Francis D.K. Ching
Materials, standards, conventions, basic assemblies
The Details of Modern Architecture , by Edward R. Ford
Key works of the 20th century with details
Illustrator human figure and tree template

Human Figure ai. Big Tree ai.