Baker at AREMA

Michael Baker Jr., Inc. will be exhibiting at the upcoming 2010 Annual Conference of the American Railway Engineering and Maintenance-of-way Association (AREMA).  The conference is being held at Hilton Orlando from August 29th through September 1st.  Look for Baker representatives at Booth #616.  

Upcoming Workshop

On Wednesday, August 25th, Stephen Clancy will be presenting a 3 hour workshop titled "Mobile LiDAR: An Overview of Surveying's New Tool" at the 55th Annual FSMS Conference in Naples, FL.


Stephen will present Mobile LiDAR basic concepts, collection, preliminary processing and final deliverables. 


Portions of the course will be made available through the blog beginning the first week in September.  

Project Planning - GPS

Expanding upon an earlier post - Measuring Systems Part 1 - Positioning, I would like to talk about planning. Perhaps the most significant factor in a successful collection is the GPS constellation.  Since the vehicle encounters many obstructions to the sky - trees, buildings, signs and other structures to name a few - it is desirous to collect when there is the highest likelihood of satellite visibility.  Sometimes this means our Mobile LiDAR crew is collecting in the early morning hours.

Utilizing simple planning software and an updated GPS almanac, we're able to input our project latitude and longitude coordinates to determine the times that we should be collecting - and when the crew should be doing something else.

The image above shows a 24-hour period for New Orleans, LA.  The number of visible satellites is but one thing we look at.  In addition, we look at the Position Dilution of Precision (PDOP) - a measure of strength of the geometry of the satellites.  Typically, the number of satellites has a direct correlation to PDOP (take a look at the dip in satellites around 08:30 above with the spike at the same time below).  However,  it does not necessarily mean that you will have a high PDOP if you have fewer satellites if the geometry of those satellites is strong - evenly distributed in the sky.

The successful completion of any project is planning.  The planning we perform for our Mobile LiDAR collections occur at many levels, each of which can vastly influence the results.

How Well Did You Do?

Following up on the Name That Car Contest, I've compiled the cars that were depicted in the point clouds. Craig is the winner with 4 correct.  Some of these proved a little more difficult than others and for good reason.  Thanks to all of you who participated - even submitting into Friday morning. I've attached some of the images.  

#1: Ford Escape - multiple people identifying it as a Mazda Tribute (same car).  I had the luxury of a photo of the front - the blue oval is unmistakable.

#2: Acura MDX

#3: Honda Accord - Going old school with the old body style.

#4: Audi A3 - The front grill gives it away.

#5: Ford Econoline:  No body missed this one.

#6: VW Beetle:  Again, no body missed this one.

#7: Chevrolet Aveo: The one nobody got.

Something that threw me regarding #7 is how the plastic bumpers appear different than the metal body in the point cloud due to the various intensities.

Time is running out...

Tomorrow at 5 PM Central, the Name that Car Contest ends.  No one has identified all of the cars correctly.  So, there is still time.  Email me your picks.

Good Luck!
Stephen