Improving Scan Accuracy: Best Practices for Interior Spaces

This article covers how to get the most accurate results from Space Mode and Floorplan Mode when scanning interior spaces. In this article, you will learn how to prepare your space, how to scan effectively, what to expect across different room sizes, and how different surfaces and fixtures behave. For more information on how scan accuracy is determined, please see How Accurate Are Polycam Scans

Before You Start

Taking a few minutes to prepare before you scan will have a bigger impact on your results than any technique adjustment you make during the capture itself.

Check Your Lighting

Turn on all available lights before scanning. Rooms with a single light source, heavy shadows, or very dark walls will produce less reliable results. LiDAR emits its own infrared signal, so ambient light doesn't power the sensor directly, but low light degrades the photographic textures that feed the reconstruction pipeline and reduces the algorithm's ability to align scan data.

Use the Flashlight Tool for Dark Areas and Corners

Polycam's built-in Flashlight tool supplements ambient room lighting when scanning dark corners and shadowed areas. Activate it before scanning any area where lighting is limited, particularly where two dark surfaces meet in a corner.

Plan Your Capture Path

Before you start recording, walk through the space and plan the route you'll take. Scanning the same area more than once can create conflicting data that the reconstruction engine has to sort out, which can lower both model quality and measurement accuracy. Aim to move through each area once in a single deliberate pass.

How to Scan

1Slow Down

Move slowly through the space, giving the sensor time to capture each surface. A rushed scan results in sparse, uneven coverage that harms both the visual output and the measurements. Both Space Mode and Floorplan Mode will prompt you to slow down when they detect excessive speed.

2Stay 3 to 6 Feet from Surfaces

Maintain a distance of 3 to 6 ft (1 to 2 m) from surfaces as you scan. For most interior rooms, this means walking around the perimeter rather than scanning from a fixed position in the center. Getting too close blurs images and limits the sensor's angular coverage. Getting too far reduces accuracy progressively, with the sensor's effective range for reliable geometry topping out at around 16 ft (5 m).

3Cover Everything, Including Floor-Wall Corners

Walk the full perimeter of the room, including corners. Thorough coverage gives the reconstruction engine the data it needs to produce complete, accurate geometry.

4Vary Your Angle

Vary the height and angle of the device as you scan rather than keeping it at a fixed position. Approaching surfaces from multiple angles produces more complete geometry.

Room Size and What to Expect

Accuracy varies with room size. Larger spaces are more sensitive to capture conditions than smaller ones.

Using Extend for Multi-Room Captures

Extend lets you continue a scan into an adjacent space after completing one area. Each extension introduces a small amount of error at the segment boundary, so measurements taken within a single segment will be more accurate than those that cross a boundary.

Understanding Surface Behavior

Different surface types interact with LiDAR in different ways. Knowing how your space's surfaces behave helps you plan your scan and get the best results from your output.

Highly Reflective Surfaces

Polished concrete, shiny tile, glass, and metal surfaces scatter LiDAR signal in multiple directions rather than returning it cleanly. In spaces with a lot of reflective surfaces, the 3D geometry of those specific surfaces may appear less detailed or smooth. Wall and room dimensions are generally not affected. Scanning at a 45-degree angle rather than straight on, and approaching from multiple directions, will give the sensor a better chance of capturing these surfaces accurately.

Very Dark Surfaces

Black or very dark surfaces absorb LiDAR signal rather than reflecting it. This is manageable under good lighting, but in dim rooms with dark surfaces the sensor may receive too little signal to reconstruct those areas reliably. Use the Flashlight tool when scanning dark walls, particularly in corners where two dark surfaces meet. Note that surface-type limitations affect the geometry and visual output of the 3D model but don't necessarily affect wall-to-wall room measurements, which are usually taken from large, light-colored surfaces the sensor handles well.

Low-Texture Floors

Vinyl plank and other repetitive, low-contrast floor materials can produce uneven floor mesh reconstruction, with waves or bumps that don't exist in the real floor. Wall measurements are not typically affected, but the floor surface in the 3D model may appear distorted.

Carpet Near Furniture

Carpet scans well in open areas. Near the base of furniture, the floor mesh may bow upward slightly where the floor meets the object. Wall and ceiling measurements are not affected.

Scanning Fixtures and Built-In Features

Polycam captures most architectural features and built-in fixtures accurately. The sections below outline what scans well out of the box, which fixture types benefit from a bit of extra technique, and what level of detail you can expect from different object types.

What Scans Accurately

The following fixture types reconstruct accurately under normal scanning conditions:

• Kitchen and bathroom cabinets
• Countertops and islands
• Built-in shelving and bookcases
• Appliances (refrigerators, ovens, dishwashers)
• Bathtubs and large sinks
• Fireplaces and mantels
• Doors and door frames
• Windows and window frames

Fixtures That Require Additional Technique

Stairs

Scan each tread and riser individually rather than sweeping up the full staircase in one pass. Position yourself directly in front of each step and get low enough to capture the riser clearly. Treat landings as separate areas and scan around them fully before continuing.

Door and Window Openings

For accurate opening measurements, position yourself inside the doorway or window opening and scan outward in both directions, then scan the frame from the front. Scanning only the face of the wall will not capture the full depth of the opening.

Kitchen Appliances with Reflective Surfaces

Stainless steel appliances can cause minor mesh distortion due to surface reflectivity. Scan at approximately 45 degrees rather than straight on, and approach from multiple angles.

Bathroom Fixtures Near Glass or Tile

Wet or recently cleaned tile and glass shower enclosures are more reflective. Let surfaces dry before scanning where possible. In enclosed shower spaces, activate the Flashlight and scan each wall from inside the enclosure at a distance of under 1 meter.

Level of Detail Considerations

Space Mode and Floorplan Mode are optimized for capturing rooms and architectural spaces. Some object types have geometry that is challenging for any LiDAR-based system to capture with full detail, regardless of technique. Room dimensions and wall measurements are not affected by these considerations.

• Thin vertical elements such as light fixture stems, floor lamps, thin poles, curtain rods, and narrow railings may not appear with full detail in the final model. Objects under roughly 1 to 2 inches in diameter don't present enough surface area for the sensor to resolve fully.
• Chair and table legs may merge with the floor surface in the 3D model. Room measurements are unaffected.
• Wire shelving and open metal racks may appear as a solid surface in the model rather than open mesh, due to the nature of their geometry.
• Hanging light fixtures with thin arms such as chandeliers and pendant lights may reconstruct partially. The fixture globe or shade often appears, while thin structural arms may not.
• Glass surfaces such as glass panels, frameless shower enclosures, and full-height windows are transparent to LiDAR. These areas are typically represented as open space in the model, which accurately reflects that the sensor cannot see through them.
• Mirrors reflect the LiDAR signal and may produce artifacts in that area of the scan. Covering mirrors before scanning will help produce cleaner results.

Does Processing Mode Affect Accuracy?

Processing mode does not affect measurement accuracy. All modes produce the same dimensional results. The choice of processing mode affects the visual quality and detail of the output.