Introduction to Reality Capture Technologies for Indoor GIS Applications
In recent years, the advent of reality capture technologies has revolutionized the way we collect and manage spatial data, particularly in indoor environments. An increasing number of scanning devices use LiDAR (Light Detection and Ranging) and 360-degree cameras to capture highly accurate 3D representations of indoor spaces. This blog explores ways reality capture data can be used to support indoor GIS applications. It also discusses some of the challenges of using reality capture data and the workflows to help address them.
Why to Use Reality Capture Data for Indoor GIS?
There are numerous situations where reality capture data can significantly enhance the creation and management of an indoor GIS:
- Missing or outdated floor plans: When CAD or BIM floor plans are unavailable or outdated, reality capture can quickly generate accurate 3D representations of indoor spaces.
- Inaccurate as-build conditions: For remodeled architecture, capturing the “as-built” conditions can provide essential data for future planning and design.
- Space reservation preview: 360-degree imagery allows you to visualize equipment and amenities in spaces like conference rooms before booking.
- Facility management: Accurate indoor data assists facility managers in tracking assets, planning maintenance, and optimizing space utilization.
- Detailed maps required for emergency response: Detailed, up-to-date indoor maps can aid in emergency response planning, and provide first responders with critical information about building layouts.
Overview of Reality Capture Systems
A growing number of companies offer portable reality capture devices. Here are three notable systems:
- NavVis MLX: Designed for closed environments, the handheld MLX offers high-accuracy LiDAR and 360/270-degree image capture, plus an innovative chest harness that frees the operator’s hands up for tasks such as opening access panels or climbing ladders.
- Leica BLK2GO: A lightweight LiDAR scanner that features hot-swappable batteries and wireless data transfer.
- FARO Orbis: Featuring GeoSLAM to reliably capture detailed point cloud data, the Orbis handheld provides a stationary data capture mode for scenarios where point cloud accuracy is paramount.
Processing Reality Capture Data for Indoor GIS
Once data has been collected using reality capture systems like those mentioned above, the next step is to process this data for use in an indoor GIS. This section will outline the necessary workflows and tools to effectively convert raw point cloud data into usable indoor GIS data.
1. Register scans: In many cases, a single indoor space may require multiple scans to capture all relevant areas. The first step is to register these scans together to create point clouds.
Registration involves aligning the scans based on overlapping features. In large datasets, consider registering scans on a floor-by-floor basis, rather than merging all scans into a single, large point cloud.
Figure 1: Registering three scans together using a stairway as a common reference
If control points were captured during the data collection process, you can use them to auto-register the scans. If no control points are available, you can utilize the vendor’s software to manually align scans by matching features in overlapping areas.
2. Georeference the point cloud: Georeferencing ensures that the point cloud data is aligned with a real-world coordinate system.
Most vendors provide tools within their software to georeference the point cloud to a suitable projected coordinate system. You can use GPS control points if they were collected during the scanning process. If no control points are available, you might want to check if the vendor’s software allows positioning by using a satellite imagery basemap.
3. Export the processed data: After processing, the next step is to export the point cloud data into a format that is compatible for use in ArcGIS Pro. This includes exporting point cloud data as LAS or LAZ file formats. If 360-degree images were captured alongside the point cloud, export these to an E57 format (which supports embedded images) as equirectangular images. You can then import the images from the E57 file using the Import Indoor Images tool.
Figure 2: A equirectangular 360-degree image captured during a LiDAR scan
4. Generate floor plans from point cloud data: Once the LAS or LAZ file is ready, you can use the Generate Floor Plan From Point Cloud tool in the Indoors toolbox in ArcGIS Pro to create polyline floor plan features in the GIS.
Quality Assurance and Editing Workflows
After generating your floor plans from point cloud data, it is essential to perform quality assurance and editing to ensure that the output meets the required standards for accuracy and usability in indoor GIS applications.
Once the Generate Floor Plan From Point Cloud tool has been run, the output will consist of polylines that represent walls, doors, and other vertical surfaces. Conduct a visual assessment of the linework in ArcGIS Pro to look for gaps, overlaps, and inaccuracies in the polylines. You can use the point cloud as a visual reference as needed to differentiate between walls and furniture as well as to identify any missing features.
Once the review is complete, depending on the quality of the linework, you may need to perform various cleanup tasks , such as:
- Close gaps in walls using the Create Features or Edit Vertices tools. Gaps may occur due to factors like large windows, open doors, or incomplete scanning.
- Delete unwanted features. For example, polylines may have been created where furniture or light fixtures were scanned but these should not be included in the floor plan.
- Reshape polylines using the Modify Features tools to adjust polylines where necessary. This includes extending, trimming, or merging lines to ensure continuity or using the Align Features tool to preserve parallel walls at a consistent thickness.
Figure 3: Using the Align Features tool to align wall polylines with a consistent offset
When modifying your data it can be helpful to:
- Enable snapping to ensure that polylines connect at vertices, and
- Use a reference grid to assist in aligning walls and ensuring straight lines.
Once editing is complete, you can validate the accuracy of the edited floor plans by checking key dimensions in the floor plan against known measurements from the point cloud and cross-referencing with any other data you may have available, such as CAD or BIM. The final polylines should represent closed space boundaries and will be used to create polygons representing building footprints (building extent), floors, and rooms in the indoor GIS.
Import Polylines to an Indoors Workspace
After completing the quality assurance and editing workflows, the final step is to import the refined polylines into an Indoors workspace. This process allows you to create a comprehensive indoor GIS that can be utilized for facility management, emergency planning, and more.
To import into an Indoors workspace, run the Import Features To Indoor Dataset tool to create polygons representing building footprints, floors, and rooms based on input polylines.
After the tool runs, you can review the output to ensure the resulting floor plan features meet your needs. If any errors or discrepancies are found, use the Create Features and Modify Features panes to make necessary adjustments. This may involve adding new features, deleting unnecessary ones, or reshaping existing features for accuracy.
After creating the floor plan geometry, you can add relevant attributes to the imported features, such as room names, space use types, and other metadata.
Import images to an Indoors workspace
Once you have floor plan features in an indoor GIS, you can import any panoramic images captured during the scanning process. Run the Import Indoor Images tool to import 360-degree photos from an E57 file into an Oriented Imagery layer. This layer can be used in floor-aware maps within Indoors apps and across the Esri ecosystem.
Figure 4: Use the oriented imagery layer in your floor-aware maps
To Recap…
Reality capture technologies, combined with effective processing and editing workflows, empower organizations to create accurate and detailed foundational data for an indoor GIS. By utilizing tools such as ArcGIS Pro and its Indoors capabilities, professionals can significantly improve facility management, emergency planning, and overall spatial data management workflows.
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