How to Use the Extend Tool in Space Mode

The Extend Tool in Space Mode allows you to continue a previously saved scan, making it easy to scan larger areas in multiple sessions. This is helpful if you have multi-room spaces or large properties that can't be completed in one go.

Plan Availability

Supported Capture Types

The Extend Tool is available for specific capture types only. This article covers the Extend Tool for Space Mode only. For information about using the Extend Tool with Object Mode captures, please see How to Use the Extend Tool for Photogrammetry Captures.

Best Practices

When to Use the Extend Tool

The Extend Tool is designed for multi-room spaces and large properties where completing everything in a single scan session isn't practical. If you're scanning a single room or a small space, a single uninterrupted session will generally give you the most accurate results. For larger spaces, splitting the capture across multiple sessions using Extend is the right approach.

Good scenarios for using Extend include scanning a full apartment or house room by room, capturing a large commercial space in sections, or returning to a space on a different day to add areas you missed in the original session.

Plan Your Scan Path Before You Start

Before starting an extended capture, think through how you'll move through the space across sessions. Starting each extension from the same area where the previous session ended gives the relocalization system the best chance of aligning your new scan accurately. Jumping to a completely different area of the space without overlapping coverage can make alignment harder.

Maintain Overlap Between Sessions

When you start a new extension, spend a moment scanning in an area that was already captured in the previous session before moving into new territory. This gives the system enough shared reference points to align the two sessions cleanly. The green grid overlay showing previously scanned areas helps you identify where this overlap zone is.

Keep Conditions Consistent Between Sessions

Try to match the conditions of the original scan when returning for an extension. Significant changes in lighting, furniture arrangement, or objects in the space can make relocalization harder, since the system is looking for visual features that match the original scan data. Turning on the same lights and keeping the space as similar as possible will help the system align sessions accurately.

Scanning Multiple Floors

If you're scanning a multi-floor property, always start your original scan on the bottom floor. When you're ready to move to the next floor, tap Done before heading to the stairs. On the processing page, tap Extend instead of Process. Once the app recognizes your location, slowly move up the stairs, scanning them as you go. This allows Polycam to register the transition between floors correctly, so each floor appears as a separate level in both the 3D model and the 2D floorplan.

How to Extend a Capture

You can extend a Space Mode capture in two ways: directly from the processing page after finishing a scan, or from an existing capture in your library. Choose the option that applies to you, then follow the shared steps below.

Option A: Extend from the Processing Page

When you finish a Space Mode scan and tap Done, you'll arrive at the processing page. Here you'll see an Extend button alongside the Process button. Tapping Extend at this stage will save a copy of the current capture in your library before the extension begins, so you'll have a record of the scan before the additional data was added.

Option B: Extend from an Existing Capture

You can also extend a capture that has already been processed. Navigate to the Space capture you want to continue in your library and make sure you're using the same device that created the original capture.

Once you've chosen your option, follow these steps to complete the extension:

1Access the Extend Tool

Navigate to the Advanced tab located on the bottom right hand side of the app.

Once in the Advanced tab, scroll to the right to find the Extend option. Tapping this will reopen the capture session and retain the tracking data from your original scan.

2Position Yourself in the Original Scan Area

For the best results, start at the place you originally scanned. The area that you already scanned will have a green grid covering it, making it easy to identify. For example, if you're scanning into a new room, begin near the doorway or transition point from your last scan. This helps the app more accurately align your new scan with the existing one.

When you successfully align with the previous scan, a message will appear informing you that relocalization was successful. This confirms that the tracking has been reestablished and you can continue scanning seamlessly.

3Continue Scanning the New Area

Scan as you normally would, following best practices: slow, steady movement and a clear line of sight to surfaces. The app will automatically merge your new scan data with the existing capture.

4Finish and Reprocess

Once you've finished capturing the new section, tap Done. You'll return to the processing screen, where you can reprocess your capture with the new data included.

During processing, you'll see a visual representation of your extended capture. Green highlights indicate the area that was previously scanned, while pink and purple highlights show the new areas that were scanned during the extended session. This color coding helps you verify that all intended areas have been captured successfully.

After extending a capture, review the entire scan to confirm proper alignment between the original and extended areas. If you notice any misalignment, you may need to recapture the transition area.

What Gets Updated

Once reprocessing is complete, both the 3D model and the 2D floorplan are updated to include the new scan data. Your floorplan will automatically reflect any additional rooms or areas you captured during the extended session, alongside the original scan.

Frequently Asked Questions

What happens to my original capture when I extend it? Will it be overwritten?

It depends on how you extend. If you extend from the processing page before the original capture has been processed, a copy of the original is automatically saved to your library before the extension begins. If you extend from an already-processed capture in your library, the extended version updates the existing capture. In both cases, the copy saved before the extension gives you a record of the scan before additional data was added.

Can I extend a capture more than once?

Yes. You can extend a capture multiple times to continue adding areas across multiple sessions. Each extension will update both the 3D model and the 2D floorplan with the newly captured data. Keep in mind that accuracy can vary more across a larger number of extensions, particularly for overall building dimensions. For more detail, see our scanning accuracy article.

What if I deleted the raw data from my original capture? Can I still extend it?

No. The Extend Tool requires the raw scan data from the original capture to reestablish tracking and align the new scan. If the raw data has been deleted, the capture can no longer be extended. Before deleting raw data, make sure you don't need to extend the capture further.

What does it mean when relocalization fails? What should I do?

Relocalization is the process by which Polycam matches your current position to the original scan. If it fails, the app was unable to find enough matching features between your current environment and the existing scan data to establish alignment. This can happen if you're standing in an area that wasn't captured in the original scan, if lighting conditions have changed significantly, or if the space has been rearranged since the original scan was taken.

If relocalization fails, try moving to an area that was clearly captured in the original scan, particularly a spot with distinctive features like a corner, a piece of furniture, or a doorframe. Make sure lighting conditions are similar to when the original scan was taken, then hold the device steady and give the system a moment to re-establish tracking.

Can someone else extend my capture on a different device?

No. The Extend Tool requires the raw scan data to be present on the device being used, and raw data is stored locally on the device that created the original capture. It cannot be transferred to another device. Only the device that created the original scan can be used to extend it.