Commands

ANALYSISZEBRA command in AutoCAD : Projects stripes onto a 3D model to analyze surface continuity

If you work with 3D models in AutoCAD and need a quick visual check of surface continuity and transitions between faces, the ANALYSISZEBRA tool is designed for that purpose. This guide explains what the command does, how to use it step‑by‑step, common problems and fixes, alternative methods to evaluate continuity, and practical tips to get reliable results.

What is the ANALYSISZEBRA command?

ANALYSISZEBRA projects a pattern of alternating stripes (a zebra/reflection pattern) onto 3D faces and surfaces in AutoCAD to help you visually evaluate surface continuity, curvature changes, and blending quality. The stripe pattern simulates how reflections would appear across the model: smooth continuous surfaces show flowing, uninterrupted stripes; geometric breaks, G0/G1/G2 discontinuities, or shading mismatches produce visible stripe discontinuities.

When and why to use ANALYSISZEBRA

  • To inspect surface blends and transitions between adjacent surfaces.
  • To verify whether two surfaces are tangent (G1) or have higher‑order continuity (G2+).
  • During modeling or quality‑control checks before finalizing a part for rendering or manufacturing.
  • As a fast, visual complement to numerical surface checks (curvature plots, analysis values).

How to use ANALYSISZEBRA (step‑by‑step)

Quick command access

  • Type ANALYSISZEBRA at the command line and press Enter.
  • Or use the ribbon: Visualize tab → Surface (or Analysis) panel → Zebra (menu name may vary by AutoCAD version).

Step‑by‑step procedure

  1. Prepare the view:

    • Switch to a shaded visual style (e.g., Realistic or Shaded) so the stripes are visible. Some visual styles do not show analysis overlays.
    • Ensure Hardware Acceleration is enabled (helps display analysis overlays smoothly): type GRAPHICSCONFIG or check the status bar graphics icon.

  2. Invoke the tool:

    • Run ANALYSISZEBRA from the command line or ribbon.

  3. Select the objects:

    • When prompted, select the surface(s) or 3D solid faces you want to analyze. You can select multiple faces or entire solids.
    • If you want to analyze specific faces, use sub‑object selection (select face rather than whole object).

  4. Choose options (may appear in command line or a floating dialog):

    • Stripe Density / Number of stripes — increases or decreases the number of zebra bands to highlight subtle curvature changes.
    • Stripe Orientation / Direction — controls the projected direction of stripes (along world X/Y/Z or view direction).
    • Flip / Invert — reverses the stripe colors to change contrast if needed.
    • Color/Contrast — adjust stripe colors or background contrast in analysis settings so stripes are visible against the object material.

    (Options vary by AutoCAD version; if a dialog appears, set density/orientation there.)

  5. Inspect the result:

    • Rotate the model and view from different angles to reveal discontinuities. Small breaks in continuity often show as abrupt stripe changes, kinks, or mismatches across edges.
    • Increase stripe density to make subtle curvature changes more visible.

  6. Turn off zebra when finished:

    • Run ANALYSISZEBRA again and toggle off, or clear analysis displays from the Analysis ribbon menu.

Practical examples (what you will see)

  • A well‑blended fillet: stripes flow smoothly across the fillet and adjoining faces with no visible kinks.
  • Tangent but not curvature‑continuous join (G1 only): stripes meet smoothly in direction but show subtle differences in curvature (stripes slightly bend differently).
  • Sharp edge or misaligned faces (G0): stripes break abruptly or jump at the edge, clearly indicating a positional discontinuity.

Why ANALYSISZEBRA might not work (common causes) and fixes

  1. Objects are unsupported type

    • Problem: You selected 2D geometry, blocks, or proxies that don’t support surface analysis.
    • Fix: Explode or convert to native 3D surfaces/solids (or select the actual surface faces). Ensure you’re analyzing surfaces or 3D solids rather than 2D polylines.

  2. Visual style doesn’t show analysis overlays

    • Problem: Current visual style (e.g., Wireframe) hides zebra overlays.
    • Fix: Switch to Shaded, Realistic, or another visual style that supports surface analysis.

  3. Graphics/hardware acceleration disabled or driver incompatible

    • Problem: Analysis overlays are not displayed or are glitchy.
    • Fix: Enable Hardware Acceleration (status bar or GRAPHICSCONFIG). Update GPU drivers and restart AutoCAD.

  4. Layer or object visibility issues

    • Problem: Layer is frozen, off, or object display is overridden.
    • Fix: Turn on the layer, clear overrides, and ensure object display is enabled.

  5. Subobject vs. whole object selection confusion

    • Problem: You intended to analyze a face but selected the whole solid or vice versa.
    • Fix: Use face selection (hover to highlight face) or use the Select tool carefully to choose the correct entities.

  6. Low stripe density or poor contrast

    • Problem: Stripes are too few or colors blend with material, making issues invisible.
    • Fix: Increase stripe density and adjust stripe/background colors in analysis settings.

  7. Very coarse mesh or low display resolution

    • Problem: Faceting of the display masks subtle curvature variations.
    • Fix: Increase mesh quality with system variables (e.g., FACETRES or surface tessellation settings) and use higher visual fidelity.

Alternative methods to analyze surface continuity

  • Curvature analysis: Use curvature plots (e.g., Gaussian or Mean curvature) for quantitative surface behavior.
  • Environment map / Reflection map: Apply an environment/reflection shader to simulate real reflections—useful for aesthetic evaluation.
  • Rendering: Produce a high‑quality render to see how light interacts across surfaces.
  • Export to a dedicated surface‑modeling tool: Tools like Rhino, Fusion 360, or specialized inspection software provide advanced zebra, curvature combs, and numeric continuity checks.
  • Mesh inspection: Convert surfaces to a high‑resolution mesh and inspect normals and vertex continuity in mesh tools.

Tips for reliable zebra analysis

  • Use multiple view angles and both orthographic and perspective views to catch different discontinuities.
  • Increase stripe density when checking subtle curvature transitions and reduce it for broad shape checks.
  • Toggle stripe orientation to run stripes parallel and perpendicular to suspected curvature directions.
  • Combine ANALYSISZEBRA with curvature plots for both visual and numeric confirmation.
  • Keep materials simple or neutral during analysis to avoid reflection artifacts from complex materials.
  • Save views after setting analysis overlays if you need to document or compare before/after changes.

FAQ

How do I toggle zebra stripes off if they remain visible?

Run the ANALYSISZEBRA command again and choose the option to clear or turn off zebra display, or use the Visualize/Analysis ribbon and select the option to clear analysis overlays.

Can I use ANALYSISZEBRA on imported models (IGES, STEP)?

Yes, but ensure imported geometry is recognized as native surfaces/solids. If faces are merged or represented as proxies, convert or repair geometry so AutoCAD recognizes the surfaces.

Does ANALYSISZEBRA provide numeric continuity values (G0/G1/G2)?

No—ANALYSISZEBRA is a visual tool. For numeric checks you should use dedicated curvature analysis or modeling tools that report continuity values.

Why do stripes appear faceted or pixelated on curved surfaces?

This often means the display tessellation is coarse. Increase tessellation quality (e.g., adjust FACETRES or other mesh/surface display settings) or enable higher visual fidelity.

Is there a keyboard shortcut for ANALYSISZEBRA?

There is no universal default shortcut. Type ANALYSISZEBRA at the command line or create a custom alias in the acad.pgp file (for example: AZ, ANALYSISZEBRA).

Can zebra analysis be printed or exported for reports?

Zebra overlays are display overlays. To include them in prints/screenshots, set up the view with zebra visible and capture a viewport image or render. For formal reports, capture screen images or create named views with analysis active.

Zebra stripes are not aligned how I want—how can I change orientation?

When running the command, check for the orientation option (view direction or world axis). If your AutoCAD version shows a dialog, use that to set stripe direction. Otherwise rotate the model/view so the stripes project in the desired direction.

My AutoCAD version does not show ANALYSISZEBRA in the ribbon—where is it?

Some releases place surface analysis tools under different ribbon tabs (Visualization, Render, or Surface). If not visible, type ANALYSISZEBRA in the command line or enable the relevant workspace (3D Modeling/Visualize) to reveal the tools.

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