Smartphone Outcrop Mapping for Joint Orientations

ISEF Category: Earth and Environmental Sciences

Subcategory: Geosciences  ·  Difficulty: Intermediate  ·  Setup: Home Setup  ·  Time: 1 to 2 Months

The Hook

A rock face can act like a fingerprint. The cracks, called joints, often record the stress history of a region. You can capture that pattern with a phone, free software, and some careful math. Then you can compare your result with published geologic maps and structural data.

What Is It?

This project uses photogrammetry, which means making a 3D model from overlapping photos. You take many pictures of a roadside outcrop, feed them into software like OpenDroneMap or Meshroom, and build a digital surface model. From that model, you can trace joint planes and measure their orientations, which describe the tilt and direction of each fracture.

A stereonet is a circular plot geologists use to show plane and line directions. Think of it like a compass map for tilted surfaces. Instead of saying, “this crack points northeast,” you can show the full three-dimensional orientation and compare many joints at once. That helps you see whether the outcrop matches the regional stress pattern reported in papers or survey data.

Why This Is a Good Topic

This is a strong science fair topic because you can ask a real geoscience question with tools you can access at home. The data come from a real outcrop, the measurements are numerical, and the analysis lets you compare your own results with published structural geology data. You will learn photography, 3D reconstruction, orientation measurement, and stereonet plotting, all of which are useful research skills.

Research Questions

• How does the choice of photo overlap affect the number of measurable joints in the 3D model?
• What is the effect of outcrop surface texture on the accuracy of joint orientation measurements?
• Does the orientation pattern from one roadside outcrop match published regional joint trends?
• To what extent do measurements from the photogrammetry model agree with direct field compass measurements?
• Which photogrammetry workflow, OpenDroneMap or Meshroom, gives more consistent joint plane estimates?
• How does lighting condition during image capture change the quality of the reconstructed outcrop surface?

Basic Materials

• Smartphone with a good camera.
• Tripod or stable phone mount.
• Portable power bank.
• Measuring tape or rangefinder for scale.
• Notebook and field sketch sheet.
• Safety vest and sturdy shoes for roadside work.
• GPS app or map app for location logging.
• Free photogrammetry software, OpenDroneMap or Meshroom.
• Stereonet plotting tool or spreadsheet software.

Advanced Materials

• Digital single-lens reflex camera or mirrorless camera.
• Surveying compass or geologic compass.
• Scale bars or coded targets for photogrammetry calibration.
• Laptop with a dedicated graphics card for faster reconstruction.
• Cloud storage for large image sets.
• GIS software for comparing outcrop data with regional maps.
• ImageJ for checking image sharpness and contrast.
• Statistical software for comparing orientation clusters.

Software & Tools

• OpenDroneMap: Reconstructs a 3D surface from overlapping photos and exports a model you can measure.
• Meshroom: Builds photogrammetry models from image sets and helps you test reconstruction settings.
• Stereonet: Plots joint orientations on a stereonet so you can compare planes and clusters.
• ImageJ: Checks image clarity, contrast, and sharpness before reconstruction.
• QGIS: Compares your outcrop location with regional geologic and structural map layers.

Experiment Steps

1. Choose one outcrop and define the exact question you want to answer about its joint set orientation.
2. Plan a photo capture route that gives enough overlap, scale, and consistent coverage of the rock face.
3. Reconstruct the outcrop in photogrammetry software and check whether the model preserves the joint traces clearly.
4. Decide how you will extract plane orientations from the model and how you will record uncertainty.
5. Build a stereonet and compare your joint clusters with published regional structural data.
6. Test which part of your workflow changes the final orientation results most, then report that sensitivity clearly.

Common Pitfalls

• Photographing the outcrop from too few angles, which leaves gaps in the 3D model and hides joint planes.
• Using shiny or harshly changing light, which creates false texture and confuses the reconstruction.
• Skipping a scale reference, which makes the model useful for shape but weak for real measurements.
• Measuring joints on weathered surfaces, which mixes true fracture traces with erosion features.
• Comparing your data to regional papers without matching the same rock unit, which makes the interpretation too broad.

What Makes This Competitive

A class-level project stops at making a model. A stronger project tests measurement quality, uncertainty, and agreement with published structural data. You can stand out by comparing two photogrammetry workflows, quantifying error against direct field measurements, or separating joint sets with a real statistical method. Clear controls and careful geologic context matter a lot here.

Project Variations

• Map joints on a limestone cliff, then compare the fracture pattern to local folding history.
• Use drone-free photogrammetry on a quarry wall or roadcut and test how lighting changes orientation accuracy.
• Compare joint orientations from two nearby outcrops to see whether the same stress field appears across the region.

Learn More

• USGS Publications Warehouse: Search for papers on joint orientation, photogrammetry, and structural geology to find regional examples and methods.
• NOAA Photo Gallery and mapping resources: Find examples of image-based terrain and surface documentation methods that can inform field photography.
• NASA Earthdata: Explore geospatial data tools and remote sensing examples that help you think about mapping scale and location.
• MIT OpenCourseWare, Introduction to Geology: Use the course notes to review rocks, deformation, and structural geology basics.
• OpenDroneMap Documentation: Read the free guides for image capture, reconstruction settings, and model export.
• Stereonet by Richard Allmendinger: Find instructions and background for plotting planes, poles, and girdles in structural geology.