The problem
EV interiors are changing quickly: no transmission tunnel, large screens and new storage spaces. Designers must turn sketches into surfaces that are smooth, buildable and respect the driver's package and vision. Students often sketch well but never learn how to build a clean instrument-panel surface model and check its quality.
Objectives
- Turn a set of cockpit sketches into a surface model on a fixed driver package.
- Build instrument-panel, screen bezel and console surfaces with controlled continuity.
- Check surface quality with Zebra, Curvature and Diagnostic Shading and fix problems.
- Produce renders and export surfaces as STEP for engineering review.
What you need
Tools and toolboxes
- Autodesk Alias (AutoStudio or Surface) — Sketching on the canvas, CV curves, Skin, Square, Rail and Boundary surfaces, Align and Surface Fillet.
- Alias evaluation tools — Zebra, Curvature, Highlight lines, Continuity check and Diagnostic Shading to judge surface quality and draft.
- SOLIDWORKS — A simple driver package: H-point, steering wheel, pedals and screen positions, exported as STEP.
- Autodesk VRED or KeyShot — Material and lighting renders of the cockpit for the design review.
Software
- Autodesk Alias 2024 or later
- SOLIDWORKS 2023 or later
- Autodesk VRED or KeyShot
Extra parts and data
- Pen tablet — Sketching in Alias Paint is far quicker with a pressure-sensitive tablet.
- Reference interior photos you take yourself — Photos of trims, grains and joints help you judge proportions without copying any brand's design.
Key concepts
- Driver package
- Fixed points such as H-point, heel point, steering wheel centre and eye point that every interior surface must respect.
- G1, G2 and G3 continuity
- G1 means tangent, G2 means curvature matches across the boundary, G3 means the rate of curvature change also matches. Visible surfaces usually need at least G2 to reflect light smoothly.
- Zebra stripes
- A reflection pattern used to judge continuity: stripes that break show G0, stripes that kink show G1 only, and smoothly flowing stripes suggest G2 or better.
- Draft for moulding
- Interior trim is moulded, so faces need draft relative to the pull direction. Alias Diagnostic Shading can show areas below a chosen draft angle.
Step-by-step guide
- 1
Define the brief and package
Write a short brief for an example compact EV: two-spoke steering wheel, a floating centre screen, a flat floor and open storage below the console. In SOLIDWORKS, model a simple package with an H-point, heel point, steering wheel position, pedal box, windscreen line and seat envelope, using example dimensions you state. Export it as STEP and import it into Alias on its own layer, locked and shown in wireframe.
Checkpoint: The package loads in Alias at the correct scale, with each element on a named layer and the vehicle coordinate axes matching SOLIDWORKS.
- 2
Sketch concepts
In the Alias Paint canvas, or on paper scanned in, draw three cockpit concepts in side, top and three-quarter views over the package. Vary the instrument-panel height, screen position and console form. Mark the driver's vision to the road over the panel and to the screen. Review the three with a peer and pick one, noting which features of the others you will carry across.
Checkpoint: Three dated concept sketches, one chosen direction and a short note explaining the choice against the brief.
- 3
Lay down key curves
Build primary curves with CV curves of low degree, for example degree 5 with few spans: the panel top line, the lower edge, the screen bezel outline and the console profile. Project or draw them in the three orthographic views so they agree in 3D. Use the Curvature comb on each curve and edit CVs until the comb changes smoothly with no reversals where none are intended.
Checkpoint: Every primary curve shows a smooth curvature comb and matches the chosen sketch when viewed from the sketch angle.
- 4
Build primary surfaces
Create the large instrument-panel top with Skin or Square between the key curves, keeping each surface a single span or a few spans where possible. Build the console sides with Rail surfaces along the console profile. Keep primary surfaces large and simple and leave transitions for later. Check that each surface stays within the package and clears the steering wheel and knee envelope.
Checkpoint: Primary surfaces cover the main forms with low span counts, and no surface intrudes into the knee or steering envelopes.
- 5
Connect surfaces with continuity
Use Align to match neighbouring surfaces at shared boundaries to G1 or G2 as required, and Surface Fillet with a curvature-continuous section for the softer transitions between the panel and console. Run the Continuity check across each boundary to confirm position, tangent and curvature tolerances. Fix any surface that fails rather than hiding it under a fillet. Keep a log of which boundaries are G1 and which are G2 so the design review can see where you compromised.
Checkpoint: Continuity check passes at every visible boundary at the level you set, for example G2 on the panel top.
- 6
Evaluate with zebra and highlights
Apply Zebra and Highlight lines across the instrument-panel top and screen bezel from the driver's view and a passenger view. Look for kinks, wobbles and stripes that pinch together. Use Diagnostic Shading with Curvature to find flat spots or sudden curvature changes. Adjust CVs and re-align until the stripes flow across boundaries. Save screenshots before and after each fix for the report.
Checkpoint: Zebra stripes flow continuously across the main boundaries with no visible breaks or kinks in before-and-after screenshots.
- 7
Add details and check draft
Model the screen bezel, air-vent openings, storage bin and a cup holder as secondary surfaces trimmed into the primaries. Set the main pull direction for the panel skin and use Diagnostic Shading for draft to find faces below an example 3 degrees. Rework faces that would trap in the mould. Check that the screen top does not block the driver's road view from the example eye point.
Checkpoint: Draft shading shows no visible faces below the minimum draft, and the sight line from the eye point to the road clears the screen top.
- 8
Render and review
Assign materials such as soft-touch grain, fabric and satin metal, and render the cockpit in VRED or KeyShot from the driver's view, the passenger view and a wide interior view. Light it with an HDRI and a soft key light to show surface quality. Hold a design review with two peers using the renders and the zebra screenshots, and record what they would change.
Checkpoint: A set of at least three renders and a written list of review comments with your decision on each.
- 9
Export and hand over
Clean the model: delete construction history where needed, name layers and surfaces, and check that trimmed surfaces close without gaps. Export the panel and console surfaces as STEP and reopen them in SOLIDWORKS to confirm they import as surfaces that can be knitted and thickened. Note any tolerance issues you see in the import. Write a short report with the brief, sketches, surface checks, renders and the handover notes.
Checkpoint: The STEP file imports into SOLIDWORKS and at least the panel skin knits and thickens to a solid without errors.
Testing & validation
- Continuity check results at every visible boundary.
- Zebra and highlight screenshots showing smooth reflections.
- Draft shading passes for moulded faces.
- Sight lines from the eye point clear the panel and screen.
- STEP import into SOLIDWORKS succeeds.
Expected results
A complete Alias cockpit concept on a real driver package, with documented surface quality, renders for review and a STEP handover that engineering can thicken into parts.
Take it further
- Build a G3 version of the panel top and compare the reflections with G2.
- Add a passenger-side screen and check the vision for both occupants.
- Make a physical scale model by 3D printing the panel.
Viva and review questions
What continuity did you use on the panel top and why?
G2, because the panel top is large and catches reflections, and curvature continuity gives smooth stripes. Hidden edges were left at G1.
How do you read zebra stripes?
Stripes that break show a gap or position mismatch, stripes that meet at an angle show only positional continuity, and stripes that bend sharply at the edge suggest G1 only. Smoothly flowing stripes suggest curvature continuity.
Why build the package in SOLIDWORKS first?
The package fixes the driver, steering and vision points, so surfaces are designed around real constraints rather than only the sketch.
Learn it at DIYguru
These DIYguru courses and programmes teach what this project needs.