Sketch to RISA: how to use it
Turn a framing sketch, a PDF plan or a truss drawing into a starting RISA-3D model, instead of retyping every node and member. Built by team BMTR at the NCSEA Big Build SE Hackathon, 2026.
Open it: khkusakabe.github.io/BMTR-sketch-to-risa · nothing to install
Quick start
- New Project. On the Projects page, click New Project. Enter a name and number.
- Upload the plan. Drop a PDF, PNG or JPG. For a PDF, pick the sheet.
- Pick the system type: 2D Frame, 2D Truss, 3D Building or 3D Misc Frame. Then click Create Project.
- Build the model. Fill in or check the inputs, or have your own Claude read the sheet and fill them in (below).
- Download the
.r3dand open it in RISA-3D. Check geometry, sections, loads and supports.
Which path does what
2D Frame
- Two-story, one-bay steel moment frame
- Bay, story heights, W-shapes, base, fixed or pinned beam ends
- Beam loads, wind and seismic at each level
3D Building
- One-story column grid plus roof beams
- Grid spacings, column height, corner/edge/interior columns
- Loads by tributary area. A "Columns only" switch skips the roof beams
2D Truss
- Opens Truss to RISA: Fink, Howe/Pratt, flat-chord or mono templates
- Upload a drawing, straighten a skewed photo with four pins, edit nodes
- Use Download sheet to bring your project's drawing along
3D Misc Frame
- Opens the tracer with your sheet loaded
- Set the scale from a known dimension, then Find lines or click node to node
- Export DXF, CSV or rows to paste into RISA spreadsheets
Every model gets basic load cases and ASCE 7-22 ASD load combinations. Check them against the standard before relying on them.
Reading a sketch with your own Claude (no API key)
On the website no key
- In the project, click Download the sheet for Claude and copy the prompt
- In claude.ai, Claude Desktop or Claude Code, attach the sheet, paste the prompt and send
- Paste Claude's answer back and click Use Claude's answer. The inputs fill in, and the tracer picks it up too
In Claude Desktop or Claude Code no key
- Add the repo's MCP server (setup in
mcp/README.md) - Show Claude your sketch: "Read it with the Sketch to RISA rules, check the sizes with me, then build it"
- The
.r3dlands in the repo'sout/folder
Have an Anthropic API key? The project page can also read the sheet directly: open Or read it from this page with an Anthropic API key.
How Claude reads a sketch
| On the sketch | Means |
|---|---|
| A pen line | A member |
| A label (C1, B1, B2) | A section set |
| A size table | The shape for each label. Struck-out sizes are ignored |
| A shaded triangle at a beam end | Fixed connection. No triangle means pinned |
| A line over hatch at a column base | Fixed base |
| Dimension strings | The geometry |
Good to know
- Your projects stay in your browser. They aren't shared with teammates or other devices.
- Your own RISA template: on the build page, add a RISA-saved
.r3dto keep your office's materials, codes and settings. - 3D Building builds one level. For more stories, extend the model in RISA or use the team's local app.
- Truss drawings: the Claude drawing reader only runs on the truss tool's claude.ai version. Templates and export work everywhere.
- More tools: All tools lists Afshin's local app (Python, reads sketches and PDFs and opens RISA) and Philip's floor-plan-columns skill for Claude Code.
The engineer owns the design. These tools build a starting model faster. Check every member, size, load, connection and support in RISA before using any result.
Code and setup: github.com/khkusakabe/BMTR-sketch-to-risa · Known issues: KNOWN-ISSUES.md