Site Capture

What you will learn

This walkthrough covers two ways to capture a site with an iPhone and turn it into a working 3D model:

• LiDAR scanning with SiteScape - fast, structured, and accurate point clouds of a room, path, or site edge.
• Photogrammetry with Polycam - photo-based meshes and point clouds that work on any phone.

At the end you will have a point cloud or a mesh you can bring into Rhino and Grasshopper to measure, section, and draw over.

Choose a method

Use LiDAR when:

• You need quick spatial coverage of a room, a path, or a site edge.
• You need a point cloud (not a textured mesh) for sectioning and measurement.
• You are working in low or uneven light. LiDAR does not depend on visible light.
• You have an iPhone Pro (12 or later) or an iPad Pro (2020 or later) with a LiDAR sensor.

Use photogrammetry when:

• You want a textured, photo-real mesh.
• You are capturing a small to medium object or a facade in good, even light.
• Your phone has no LiDAR sensor. Any recent iPhone or Android works.

Many projects use both. LiDAR gives you the overall site envelope; photogrammetry gives you detail objects with color.

What you need

• An iPhone Pro (12 or later) or iPad Pro for LiDAR. Older iPhones and Android phones can still run Polycam in photo mode.
• The SiteScape app (free) and the Polycam app (free tier, paid plans for full export).
• Steady hands, a charged battery, and storage space for the scans.

SiteScape (LiDAR)

SiteScape captures point clouds with the iPhone LiDAR sensor. It shows the captured points in real time as an AR overlay, so you can see gaps as you scan and fill them before you leave the site.

Steps:

1. Install SiteScape from the App Store (link in Resources).
2. Create a free account. Local export does not require a paid plan.
3. Start a new scan. Point the phone at the area and press capture.
4. Walk slowly along a set path and keep the phone steady. Overlap your passes so the AR overlay shows no large holes.
5. Pause and review. Rescan any area that shows as a gap.
6. Tap export and choose a format. SiteScape exports PLY, E57, and LAS/LAZ point clouds.

Notes on accuracy:

• Expect roughly plus or minus 1 inch (2 to 3 cm) in ideal conditions.
• Drift accumulates over long scans. Break a large site into smaller overlapping scans and register them together later if you need to.
• One scan holds up to about 12 million points and covers roughly 2,000 square feet.

Polycam (photogrammetry and LiDAR)

Polycam works two ways: Photo Mode (photogrammetry) and LiDAR Space Mode (on LiDAR devices).

Photo Mode (photogrammetry):

1. Install Polycam (App Store or Google Play, link in Resources).
2. Choose Photo mode and pick object or scene.
3. Walk around the subject and take overlapping photos. Aim for 60 to 70 percent overlap between shots.
4. Keep the light even. Avoid hard shadows, reflections, and moving people or foliage.
5. Let Polycam process the capture on the device or in the cloud. Review the mesh.
6. Export. The free plan exports GLTF only. To export OBJ, FBX, STL, or point clouds you need a paid plan.

LiDAR Space Mode:

• Use this on a LiDAR device for a fast point cloud of a room or a site, similar to SiteScape.

Polycam export formats by plan:

• Free: GLTF only.
• Basic: OBJ, FBX, GLTF, DAE, STL, USDZ, images, video, and blueprints.
• Business and Enterprise: point cloud formats (LAS, PLY, PTS, XYZ, DXF, geo-referenced LAS) and floor plans (PDF, DXF, PNG, SVG, CSV).

File formats cheat sheet

• E57, LAS/LAZ, PLY, XYZ, PTS - point cloud formats for Rhino, CloudCompare, and Grasshopper.
• OBJ, FBX, GLTF, STL - mesh formats for Rhino, Blender, and rendering.
• For Grasshopper point cloud work, export XYZ or PTS (plain text) when you can. They are the easiest to read and section.

Into Rhino and Grasshopper

Rhino 8 opens point clouds directly. Import an E57, LAS, PLY, or XYZ into Rhino, or read an XYZ/PTS text file in Grasshopper. Then use the point cloud section definition to cut a section and draw the line.

Field practice

• Capture a scale reference (a known dimension, a person, a tape measure) so you can verify scale later.
• Check a known measurement in the app before you leave the site.
• Scan more than you think you need. Deleting points is easy; filling gaps later is not.
• Back up exports to the cloud or a drive before you leave the site.

Resources

• SiteScape on the App Store: https://apps.apple.com/us/app/sitescape-lidar-3d-scanner/id1524700432
• SiteScape background (AEC Magazine): https://aecmag.com/reality-capture-modelling/sitescape-lidar-scanning-on-the-iphone-ipad/
• Polycam: https://poly.cam
• Polycam export formats: https://learn.poly.cam/hc/en-us/articles/27756102599572-What-File-Types-Can-Polycam-Export
• Polycam pricing: https://poly.cam/pricing