3D Scanning: Versatility Factors for 3D Scanning Software
Professional Surveyor Magazine - March 2010
Read Part 1
Read Part 2
Organizations often place great importance on a laser scanning systems’ versatility to support a wide variety of projects. Parts 1 and 2 of this series (October 2009 and January 2010) discussed versatility factors for a laser scanner. Part 3 covers key versatility factors for the all-important software. First, I’ll cover a couple of general aspects and then follow a typical project workflow.
The more flexibility that an organization has in deploying staff for processing high-definition survey data, the better. Look at the software’s user interface and workflow options and how they fit your staff’s skills. But also be careful here. Today’s simple, easy-to-learn software, such as point cloud plug-ins for CAD and/or CAD software with embedded point cloud capabilities, often isn’t as versatile as more heavy-weight, standalone point cloud software.
IT and Commercial Aspects
Consider the various ways you can purchase from the vendor and how you would implement point cloud software in your organization, including licensing schemes. Starting with free point cloud viewers, you can move up to some software that runs in a free mode without any license but can be activated to full capabilities with license purchase. Some licenses are locked to one computer while others use a license server or dongle that lets multiple users share a floating license.
Some software can be purchased via rental or on a per-use basis. The other end of the spectrum is the increasingly popular site licensing or enterprise licensing: basically an all-you-can-eat type of licensing and purchase. Client-server point cloud software allows another level of versatility where groups of individuals can log into a central system and collaborate on the same data at the same time.
The more options that a software vendor offers for licensing and implementation, the better from a versatility standpoint. It’s not unusual for organizations to grow and modify their office implementation over time. So, also look for scalable solutions.
Finally, assess any office hardware, IT system upgrades, and/or compatibility issues with your existing software that need to be sorted when your staff starts processing millions of points. Generally IT upgrade costs are small, but they can be unpleasant surprises if you haven’t done your homework.
Registration and Geo-referencing
The ability to accurately tie together and geo-reference point clouds collected from different positions is essential. There are several field and office ways to do this; however, depending on the nature of the scene being scanned and site logistics, not all methods are optimal or, in some cases, even feasible. In addition, due to the criticality of this step for project accuracy, the ability to use different registration methods on the same project adds valuable project QA by double checking or “tightening-up” registrations. You will often hear users say that versatility in registration options is a big plus.
Registration options include traverse methods, the use of scan targets, and/or cloud-to-cloud registration, in which point clouds are aligned to each other via their overlap areas. Some software provides only one method of registration, while others may provide all options. Using a combination of methods on the same project is often the optimal solution.
For data import/export, versatility aspects apply not only to laser scan data itself but also to CAD model data, control data, and image data. For laser scan data import, see if file types include formats for the most popular types of laser scanners and, of course, for your organization’s specific laser scanner(s). If you use the same software in the office that was used in the field to collect the data, then no data conversion is necessary. Otherwise, look for published binary formats that are efficient to work with; traditional ASCII-based file formats (including PTS and PTX formats); and/or standard aerial lidar data format (LAS).
Another factor is the extent to which software supports metadata in addition to X, Y, Z data. Metadata can include intensity-of-return information, which is helpful for visualizing high-definition survey data, and normals, which provide information about neighboring points and are beneficial for processing scan data into deliverables. Import of control data allows you to bring in control from other sources to help tie-down your survey.
On the data export side, look not only for formats (e.g. XML, DXF, and DGN) or conversion tools for export to CAD applications, but also formats useful for export to other point cloud software. Many users have more than one point cloud software package, so check their compatibility. For this reason, many users prefer software packages that are all developed by one vendor, as this helps ensure compatibility.
The capability to import CAD models into point cloud software can be useful for comparing proposed designs with existing condition scan data. Doing this comparison inside point cloud software can be more efficient than doing it inside CAD software, as point cloud software is generally better at handling large scan data files.
Data File Size
The bigger the file sizes that can be ingested and managed efficiently, the better for software versatility. Software packages today need to handle billions of points. As discussed below, it’s not just the ability to import and access large amounts of data; it’s just as important to be efficient in viewing, navigating, and processing these large data sets into deliverables.
Data Cleanup and Preparation
A typical first step in working with data collected from a laser scanner is removing or “hiding” spurious points such as those collected from vehicles or people that pass in front of a scanner. There are many ways to remove spurious data, including automated ones. Data cleanup can also include unification of multiple point clouds, which optionally reduces point redundancy in areas where scans overlap, and various schemes for decimating point clouds. Not all data cleanup tools are optimal for every situation, so the more options for this step, the better.
Discerning information from looking at high-definition survey data on a computer screen can be challenging. So, the ability to let users effectively visualize high-definition survey data is often key to office efficiency.
Many tools can aid visualization, from false-coloring to true-coloring and from lighting-and-shading aids to specific viewing modes that automatically take the user to a particular view. An example of a useful viewing mode is a single command that automatically takes you to a view of the scanned scene from where the scan head was. Other useful viewing modes include automatic switching of the user’s view to an overhead plan view, a section view, an outline view, a perspective view, etc. Still other useful viewing tools let users automatically select the displayed point density from various levels of decimation. Save and restore commands are beneficial for especially valuable views. As with data cleanup tools, not all visualization tools are useful for every situation, so the more visualization tools, the better.
Like visualization, navigating around and through 3D point clouds on a 2D computer display can be challenging, yet it’s critical to office efficiency. Also like visualization, not all tools for navigating point clouds work best for all situations. So, again, versatility here is invaluable.
Navigation tools can include segmenting the point cloud into spatially indexed sections (e.g., into bays for a manufacturing plant); key plans with clickable icons that can automatically take you to specific scanner locations; clickable scanner location icons within point clouds; limit boxes that hide all other scan data and can be subdivided into smaller boxes and managed as a group; tools that allow a user to toggle between a view in standalone point cloud software to the corresponding view in a linked CAD application; automatic navigation to scan targets, etc.
A very large number of deliverables are possible from a high-definition survey (see the April 2009
issue). The more types of final or intermediate deliverables that your point cloud software can create, the better from a versatility standpoint, as these can be key to getting the most from an investment in laser scanning.
An intermediate deliverable might simply be a text file of feature-coded points or a 2D map or a 3D surface. Although they seem natural and familiar, not every point cloud software can do all of them or do any of them well. Versatile integration with your standard final deliverable tools such as CAD or COGO databases or report software is a must.
Beyond these traditional deliverables, users can also provide clients with enhanced 2D maps, different types of scanned scene imagery, slices through point clouds, various types of 3D models, point cloud data files, scanner location maps linked to scan data, fly-through movies, and scan file sets that can be used with free, web-based viewers.
Consider also the end-use applications or target markets: civil, industrial plant, structural, architectural, forensics, heritage, etc. When processing or modeling point cloud data into specific objects, the more types of objects and geometric primitives that are supported, the better. For example, can the software convert point cloud data into process plant objects (e.g. pipe runs, elbows, reducers, flanges, steel beams, tie-points, etc.), architectural features, forensic maps, etc.? Can the point cloud software access parts catalogs/libraries or provide links for creating intelligent models?
Some organizations find over time that clients start to ask them to do simple design tasks based on high-definition surveys. An example is the production of clash reports, whereby the client gives a proposed design to the surveyor and asks the surveyor to locate and quantify the extent of any clashes of the proposed design with existing conditions. To do this, it’s valuable for point cloud software to be able to import design models and to automatically identify clashes with existing conditions.
The lower the office deployment cost, the better from a versatility standpoint, as you will be more likely to win projects, gain clients, and/or earn more profit. Deployment costs for office software are based on multiple factors:
- the office software’s productivity, translated into the number of labor hours needed for a project and cost per labor hour,
- the software’s total purchase cost and related ownership costs (e.g. maintenance and training) as allocated to projects, and
- ancillary costs, such as any IT system upgrades.
Note that I have lumped software’s productivity factors into a “deployment cost” factor when discussing software versatility. Differences in office productivity between software packages can be quite significant. Vendors often promote specific software productivity features that each vendor claims make their software the best, but users should consider the bigger picture of overall deployment cost and versatility to determine which software is actually best for them.
Tip: Review the Complete Technical Specs
To assess the versatility of any specific software, a good place to start is to look over the software’s complete technical specs, just as you look at specs of a scanner. Vendors should be able to provide you with complete software technical specs if you ask.
In general, the more spec items, the more versatile the software. In addition, you can use these tech specs as a guide when you get a demo of the software. You can get a sense of which software features would most benefit your organization, plus it will make it easier for you to compare advantages of one software with those of another.
Many versatility factors determine the overall versatility of scanning hardware and software. From a practical standpoint, laser scanning systems with the best overall versatility are also the most popular in the market, as most survey organizations value versatility quite highly.
About the Author
Geoff JacobsGeoff is senior vice president, strategic marketing for Leica Geosystems, Inc.
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