Baker's Dozen: 13 Laws of Mobile LiDAR

A little over a month ago, our Ridgeland office hosted a visit by Baker's CEO, Brad Mallory.  During a presentation of projects our Transportation group was working on throughout Mississippi, it was quickly observed that several of the slides had 13 projects listed - a Baker's dozen.

From that meeting, an idea was born to develop "Baker's Dozen: 13 Laws of Mobile LiDAR."  These Laws were developed after much thought and consideration.  In coming posts, I will explain each of the Laws in detail providing further explanation.  

Without further ado, I unveil the Baker's Dozen: 13 Laws of Mobile LiDAR (also currently being chiseled on a slab of granite):

1. Too much is better than not enough.
2. Sometimes more is just more, not better.
3. Hard drives are cheap, time isn’t.
4. Consistency counts; stop guessing.
5. When someone wants “full planimetrics,” they really don’t.
6. The stated laser range is X’, but the lasers are only capturing data to Y’; and Y is definitely less than X, yet nobody can tell you what Y is…
7. The data you capture is only as good as the applied control.
8. Today’s best practices will be tomorrow’s old habits.
9. Field vs. office time ratios are pipe dreams.
10. Mobile LiDAR systems are not created equal, and neither are the operations behind them.
11. Off-the-shelf processing software will only do 50% of what you need it to do.
12. When the system encounters issues, take a breath and reboot.
13. Mobile LiDAR is not all fun and games, but it does feel like it some days.  

Feel free to let me know what you think.  Perhaps we can have a committee gathered to debate them or formalize some agreement.

Cheers!
Stephen

Riding the Rails

Back in March, Baker performed a Mobile LiDAR collection of a high speed rail corridor encompassing approximately 240 miles (opposing tracks along the same corridor).  Now that the primary products have been delivered, I took an opportunity to create several screen captures of the collection.  The two images below present different views of the same section of track.

Facing northwesterly, the screen capture clearly depicts the ability to capture a number of elements beyond the rail features.  The handiwork of local "artists" is evident thanks to the intensity returns from the system.

An opposite view from the image above shows the extent of overhead electric distribution, communication and fiber optic  utilities.  Also present are supporting guy anchors, a single mile post and other features necessary to develop engineering design drawings.

The detail of information captured in a single collection is quite impressive.  In addition to the planimetric feature extractions and track geometries, Baker developed a digital elevation model following constraint of the Mobile LiDAR collection.

Let me know what you think.
Stephen

Complexities of a Mobile LiDAR Survey

A few weeks ago, my fifth article for LiDAR News was published.  The article, titled "Complexities of an Urban Survey," discussed our recent collection of Charleston, WV.  The collection encompassed an incredibly varied urban and rural environment along 350 miles of public rights of way (collected in opposing directions).  Through project planning, we attempted to mitigate or minimize the known challenges we were going to face.  

The images presented in the article are shown below:

As the article states, we established control target layout for a local survey firm.  Above is a representation of a Google Earth KMZ depicting the control point layout.

Each SBET (sometimes a few a day due to weather) were exported to a Google Earth KMZ to perform cursory review of status.

Our Mobile LiDAR crew and Program Manager, Aaron Morris, provided an "Open House" to city staff and the media.

My next article for LiDAR News will be on the Position and Orientation System.  Should you have a topic to consider, leave me a comment.

Cheers!

Stephen

ASPRS - Mobile Mapping Committee

The ASPRS Mobile Mapping committee meeting took place on May 2^nd at ASPRS's Annual Conference held in Milwaukee, Wisconsin.  Dr. Craig Glennie from the University of Houston, Texas is the new Chair and  Dr. Srini Dharmapuri, LiDAR Scientist at Baker is the Vice Chair.

The meeting began with a discussion of the some of the significant activities in the mobile mapping community over the last year, including:

• The release of mobile laser scanning specifications by Caltrans
• The currently pending TRB contract to develop guidelines for mobile LiDAR in transportation applications
• The formation of the GTMA (Geospatial Transportation Mapping Association)

After this brief summary, it was decided that the committee should concentrate on the formation of a best practices and guidelines document, with the goal of having an initial draft prepared for ASPRS 2012.  To this end, a proposed framework for this document was presented (and given in the attached word file). 


The Mobile Mapping committee is looking for volunteers to assemble “best practices document” and interested parties may get in touch with Dr. Craig Glennie and Dr.Srini Dharmapuri. 


Good luck to Craig and Srini as they lead the endeavor to establish standards and best practices for the Mobile Mapping industry.


Click to download the Mobile Mapping Committee Presentation.


Cheers!
Stephen

No Place for Survey Crews

Earlier this year, we were tasked to perform a Mobile LiDAR collection of an Interstate tunnel (2 lanes in each direction - measuring 0.8 miles in length).  The tunnel is in a heavily trafficked urban corridor where closures required by traditional surveying, even in the early morning hours, were completely out of the question.

Due to the constant, unrelenting traffic, we performed the collection shortly after midnight.  We collected each of the 4 travel lanes at or slightly below posted speed limits - slowing down or speeding up to minimize laser shadows from other vehicles.  Following the collection, our LiDAR processing staff and Applied Technology Group produced the final products.

First, our LiDAR processing staff adjusted the passes to ensure coincidence.  Then they made quick work of removing other vehicles from the point cloud.  Then, they turned over the tiled point clouds for modeling.

An image of the point cloud with vehicles removed, but tractor trailer model added.  Notice the pothole in the bottom left hand corner of the image. 

Our Applied Technology Group utilized the cleaned point cloud to create a rendering of the tunnel in MicroStation.

In the article I wrote for LiDAR News last week I made the statement "if you can’t see it, the system isn’t measuring it." The below image is directly disputing that statement - which I don't quite mind in this case.  

The image shows a cross-section of the tunnel.  Notice the arc above the "box" tunnel.  The arc represents returns from the actual tunnel ceiling (extent of bore) that were measured through small (1") joints in the false ceiling.

Perhaps what is most fascinating to me is not that the system captured this information, but how it will be exploited by our client.

Cheers!
Stephen