Digital Coast

I run into trouble trying to use the TIFF format for lidar derived DEMs, because there is no standard tag for a “no data” value.

We’ve changed the way we store our point data so it is compressed and that has allowed us to put the data where you can pick up big chunks at once. 

Hurricane Sandy has given the East Coast quite a wallop. As emergency management and other organizations try to get a handle on the extent of the problem and as a nation we begin to patch ourselves up, we thought it might be useful to provide some of the geospatially oriented information that might be relevant. I plan to update this as we get more information, it certainly isn't all encompassing yet.

If you use elevation data for your work, you probably know that lidar availability in the United States is patchy, inconsistent, and just plain confusing.

It seems like every day I hear a statement about high-resolution lidar that bugs the heck out of me. I even hear it from our staff at the Center. So, I thought I'd write a little entry about it and see if any of them pick up on it.

A frequent question we hear is, "What can you see with lidar?" Since not all lidar is created equal, it might be easier to look at it from another direction, one which I'm sure is often on people's minds.  That is, "What lidar specifications would be good enough to detect zombies?" Given the recent warnings from the CDC about preparedness for a zombie apocalypse, there is a clear need to get a head start in zombie detection.

Every so often I get a question from someone that makes me realize I haven’t done a good enough job of describing what’s going on in the lidar distribution system of Digital Coast and why we do certain things that might appear crazy.  The most recent one involved a data set that is about five years old and a user was trying to fill some gaps in their copies of the original data.  When they downloaded the data from Digital Coast, they were showing just over half a foot vertical difference from the originals, though the points were horizontally right on.

Over the last year we’ve been working on mapping the possible inundation that sea level rise would bring to the coastal community. We quickly ran into a serious question. What amount of rise can we map given the accuracy of the elevation? This ought to be an easy question. Surely there are mapping standards we could follow. Alas, there are multiple mapping standards and what you pick depends on what you think you’re doing and the assumptions you make about that process. I’m going to look at a few options for looking at the problem and maybe a different way to think about mapping standards.

The staff at Coastal Services Center get a lot of technical questions and provide a lot of answers, but those answers don’t generally get published even if they might be common issues.  Sounds like material for a big page of frequently asked questions.  However, a big FAQ doesn’t allow other people to add comments, clarifications, or new ideas.  In addition, there are times when we’d like to put some ideas out there for the community to chew on without requiring or implying the corporate seal of approval.