Yazoo City Tornado: Part 3 – Visualization

Wrapping up our posts on the Yazoo City tornado, where we previously discussed mobilization in Part 1, damage surveys in Part 2, we are completing the trilogy with data visualization.  Prior to, and following the field collections, the one question we kept getting asked was whether we’d get data that could be used for anything other than debris volume calculations, or photo interpretation; after all, no one has done this before, and if you’ve got a big pile of jumbled debris, will the resolution be fine enough to enable the processing staff to recognize what they are looking at?  The results are a resounding YES!

The key is to create a seamless colorized point-cloud, which combines the LiDAR data (including laser return intensity) with the RGB values from the captured images (see Measuring Systems - Part 2); bringing the 2D images to life in a 3D environment.

Image of the Save-alot Grocery Store

Yazoo Motors Service Shop.  Building 2 (left) lost the roof and most of the back wall.  While building 3 (far right), a mere 80' away was completely leveled.  Click here to see the original photograph of building 2.

Close-up view of collapsed wall in above image.  The high-density of LiDAR points makes it easy to count each cinderblock, or identify the electrical service still attached to the façade.

Yazoo City Tornado: Part 2 – Damage Surveys

Continuing our previous post on the Yazoo City tornado (See Part 1), it’s sometimes difficult to really wrap your brain around the phrase “catastrophic damage”, or “utter devastation”, and visualize what that really means.  The use of Mobile LiDAR in damage surveys/assessments aids in the visualization component by not only capturing images (a picture is worth a thousand words), but also by creating a 1:1 model of the real-world.  We can all pretty easily visualize a forest or a mobile home, but each of us would have a different interpretation from a news report that simply states “mobile homes and forest leveled by tornado”.  Would you picture this?

Quantifying damage and putting a real measurable value to comprehend “debris”, needs more than just superfluous adjectives (or expletives if you’re so inclined).  You need a concrete method to calculate volumetrics (how many dump truck loads is that?), assess damage, and provide usable data for disaster modeling.

The above image is of the Mississippi DOT Maintenance Facility (Bing Bird's Eye - Google StreetView).  While, below is a picture of the Yazoo Motors Service Shop (Bing Bird's Eye).

Part 3 in the series will be forthcoming.  It will address visualizations from the collected data.

This isn’t Kansas Toto

Since we brought our system online last September, we haven’t had the opportunity, or need, to showcase our rapid-response capability.  That changed with the devastating set of storms that rolled into the deep-south on April 24^th, which spawned an EF4 tornado that was on the ground for an astonishing 149 miles!

On the Move

Once the debris settled into place, we quickly re-routed the system to Yazoo City, MS, which at the time was en route to Florida for a project with the DOT.  We picked Yazoo City because it was one the harder hit areas (the wedge funnel was over 1.75 miles wide in Yazoo City), and it presented the opportunity to perform widespread damage assessments.

  

Johnny on the spot

Five hours (and 280 miles) after re-routing the Mobile LiDAR system, we were on-site.  We’ve always said that the key to the system is mobility, and the ability to rapidly deploy for emergency situations.  When we rolled into town, we knew our response couldn’t have been any better when only the emergency management responders, local media, and storm-chasers were on the scene.  The picture to the right shows the remnants of Hillcrest Baptist Church and the devastation a storm of this magnitude can cause. 

For anyone that’s watched the Discovery Channel’s Storm Chaser’s television series, you’ll likely recognize Reed Timmons’ TVN “Dominator” tornado intercept vehicle in the below image.  Although the Dominator is built to withstand high winds and hail…we think our system looks better.

This is the first in a series of blogs showing information collected in the aftermath of the late-April tornado that devastated Yazoo City, MS.  Baker has had a long presence in Mississippi - our Jackson office is the second oldest in our firm at 60+ years.  Our thoughts are with those you have been impacted by this storm.

The Size of Data - Zettabyte?

I spent a few hours this past weekend helping my wife clean out our home office.  In all the clutter, she found a case for 3.5" floppy disks containing about 50 disks. While we perused the labels on the disk - HP Printer Driver Disk 1 of 3, GIS Topics (senior elective), endless blanks - we searched the house for a computer with a disk drive capable of determining the need to keep any of them.  Of the 3 computers in our home, we came up empty handed.  


After chatting a bit about the need to keep things we didn't even know existed in the first place, my wife relented and I threw them in the garbage.  Then I promptly removed them from the garbage. As my wife brought to my attention, the same person who's going to rummage through garbage to find personal information, probably has a drive that somebody else threw away. So, as I began destroying the disks, I contemplated the size of the data they contained.  After all, it's interesting to see how technology, and storage, has developed over the past years or decades.


Over the past 20 years, we've witnessed the size of data and what we store grow to astronomical levels - levels that even require the invention of new words.  From kilobytes, megabytes, gigabytes, terabytes, petabytes, exabytes to zettabytes - One zettabyte is equal to one million petabytes, or 1,000,000,000,000,000,000,000 individual bytes. (The yotabyte is next.)


To give you an idea of the amount of data we capture with the system, I've compiled a table presenting rates given the camera and laser frequencies:

Measurement Frequencies	50 kHz	100 kHz	200 kHz
Camera Rates
Cameras Off	3 MB per second	6 MB per second	12 MB per second
1 frame per second	13 MB per second	16 MB per second	22 MB per second
2 frames per second	23 MB per second	26 MB per second	32 MB per second
3 frames per second	33 MB per second	36 MB per second	42 MB per second

Looking at these numbers, it would take about 0.034 seconds to fill up one of those disks I threw away - when the system is working at peak performance. Our operators would need fast hands and a steady supply to keep up with the system. Thankfully, we have a constant supply of hard drives to transfer information from the vehicle to our processing facilities. 


With the advancements in computer processors, memory, video drivers and software, we have come a long way with what we're able to effectively manage.  The slide show prepared for Baker's 70th Anniversary provided me a glimpse of where we've been...  

I can't imagine processing Mobile LiDAR data with that computer - although it cost significantly more than the systems we use today.

Happy 70th Baker!  Here's to another 70!