Scan to Sketch — Teacher Guide
Free · No accounts · Works on Chromebooks, computers, iPhones, and iPads
Scan to Sketch lets students turn a 3D scan of a real object into a technical drawing (orthographic and isometric views with dimensions and a title block) and an industrial-design marker rendering with callouts. Everything runs in the web browser. Nothing is uploaded.
Quick start (5 minutes)
- Open the app and tap Try a sample object, or open the 📚 Object library (101 everyday objects in 7 categories) or tap 🎲 Random object. No scan needed. Turn on Broken to get a chipped, cracked, dented, bent, or snapped object with a repair challenge; Scan-like makes objects slightly bumpy like a real phone scan. Every scan a student opens is also saved automatically under 📁 My scans in the library (on that device), with its real size once set.
- 3D Model tab: drag to turn, pinch or scroll to zoom. Tap Measure, then two points. Tap Set real size and enter a measurement taken with a ruler or calipers.
- Drawing tab has three steps: 1 Original drawing (front, top, right side, and isometric views appear automatically; add Dimensions, Labels, Notes, and Arrows; fill in the Title block), 2 Redesign (tap ✨ Start from my scan to get the object already sketched, then drag corners, edges, or whole shapes to change it; or draw new sketches and extrude or revolve them; early preview), and 3 New drawing (a technical drawing generated from the redesign).
- Rendering tab: choose Original scan or My redesign, pick an angle and marker colors, then + Add callout to label features in handwriting.
- Save & turn in: download the PDF (drawing plus rendering) and the project file, then upload them to Google Classroom.
Before class: scanning
- Students need a free phone scanning app, for example Scaniverse, Polycam, or KIRI Engine. Free features change over time, so try one yourself first. One phone per group is enough.
- Good objects are fist-sized to shoebox-sized and not shiny, clear, or solid black. Mugs, staplers, tape dispensers, game controllers, shoes, and tools work well.
- Export as GLB if possible (one file with colors). OBJ, PLY, and STL also work. Unzip .zip files first.
- Get files to Chromebooks through Google Drive: save from the phone to Drive, then on the Chromebook click Open a scan → Google Drive.
- The in-app How to scan guide walks students through all of this.
A sample lesson sequence
About five 40–45 minute periods. Adjust to your course.
| Day | Students… | In the app |
|---|---|---|
| 1 | Choose an everyday object that could be repaired or improved. Scan it in pairs and save the file to Drive. | How to scan guide |
| 2 | Measure the real object with calipers, set the real size, and compare other scan measurements to the real ones. How accurate is a phone scan? | 3D Model: Measure, Set real size, Turn the model |
| 3 | Produce a technical drawing: choose the front, discuss scale, add dimensions and notes, and complete the title block. | Drawing tab |
| 4 | Create a marker rendering and call out materials, features, and problems they noticed (worn, broken, hard to use). | Rendering tab |
| 5 | Turn in the PDF and project file; peer critique. Sketch improvement ideas by hand, ready for the redesign editor coming in version 2. | Save & turn in |
Discussion and extension ideas
- Accuracy: scan measurements vs. caliper measurements. What is the percent error, and why?
- Scale: why does a 1:2 drawing print at half size? Print a 1:1 sheet and lay the real object on it.
- Projection: why is the top view above the front view (third-angle projection)? Why can't you dimension an isometric view?
- Communication: what does a rendering communicate that a technical drawing doesn't, and the reverse?
Turning work in
- Save & turn in → PDF creates page 1 (drawing sheet, prints to scale) and page 2 (rendering). Files are named automatically, for example Shelf bracket - Jordan Rivera - drawing.pdf.
- Project file (.s2s) holds the whole project. Students (or you) can reopen it on any device with Open a scan. Ask for it if you want to look at or grade the live work.
- Google Classroom: open the assignment → Add or create → File → choose the file from Downloads → Turn in.
- iPhone/iPad: downloads open in a preview; use the Share button to save to Files or Google Drive.
Standards
In the app, open ★ Standards & more to see which standards each activity supports. New York is available now: the NYS Learning Standards for Mathematics, Science, and Technology (Standard 1 and Standard 5, quoted from NYSED documents) and NYS P-12 Science engineering design (ETS1). The panel clearly labels any wording not yet confirmed against NYSED. Matches between activities and standards are suggestions for teachers to review, not an official NYSED alignment. Other states are listed as coming soon.
Troubleshooting
| Problem | Try this |
|---|---|
| "3D isn't available" or a blank 3D area | Update Chrome. On managed Chromebooks, ask IT whether hardware acceleration or WebGL is turned off. |
| A file won't open | Use GLB, OBJ, PLY, or STL. Unzip .zip files first. Export again from the scanning app (GLB works best). |
| "Point cloud" message | The scan is dots, not a surface. Export it as a mesh (GLB or OBJ) instead. |
| Slow on an older Chromebook | Close other tabs. The app automatically simplifies big scans; very large files (over 300 MB) may still struggle, so export a lower-detail version. |
| Messy lines on the drawing | Choose Fewer lines on the Drawing tab, or rescan a matte object in even light. |
| Drawing sideways or upside down | On the 3D Model tab, use Turn the model until the object's front faces you when you tap Front. |
| Work disappeared | Auto-save lives in that browser for that user. It doesn't follow students to other devices, and it's erased by clearing browsing data or by Chromebook Guest mode. Have students download the project file at the end of each class as a backup. |
Privacy information for administrators
- No accounts and no sign-in. The app does not collect names, emails, or any personal information.
- No data leaves the device. Scans are opened and processed entirely in the browser. Work is saved in the browser's own storage (IndexedDB) on that device. A student's name typed into the title block stays on the device and appears only in files the student chooses to download.
- No tracking. No analytics, no cookies, no ads, and no third-party scripts, fonts, or services. All libraries are stored with the app.
- Technically enforced. The app uses a Content Security Policy that tells the browser to block any connection to other websites.
- Hosting. The app is a set of static files on a free static host. Like any website, the host receives the standard technical information a browser sends when it loads a page (such as IP address and browser type). The app itself sends nothing else.
- Deleting data. Clear the site's data in the browser settings, or open a new project in the app.
- Open source. Built with free, open-source libraries: three.js, meshoptimizer, Draco, jsPDF, svg2pdf.js, and the Architects Daughter font.
Coming soon
- Built-in scanning: phone video turned into a 3D model on a school gaming PC with free photogrammetry software (COLMAP or Meshroom).
- More redesign tools: the redesign step is in early preview with sketch, extrude, and revolve; editable dimensions, holes, rounded edges, and STL/STEP export are on the way.
- More states' standards and college-level features.