What Kind of Camera Should I Buy?

I get asked this question a lot though I don't really think of myself as a good resource for shopping advice. That said, I can offer a few things to think about when purchasing a camera. 

Resources for Research
If you want to look at cameras side by side, DPReview has a nice interface for doing that. It is recommended that you use this and learn what the specs mean.

Another good site with great reviews is The Digital Picture.

Here are some things I universally recommend (which are nearly universal on quality cameras now): RAW image support, a decent selection of lenses or an adapter to a type of lens with a decent selection, and 10+ megapixels.

Mirrorless cameras are lighter and take up less space. This is advantageous for cavers since there's less stuff to carry around. The disadvantage is that the energy consumption. Active LCDs take a lot of energy, so you'll want to have a few spare batteries charged and laying around. Also, they do not sell battery grips for most of the mirrorless cameras that I have seen.

SLRs are heavier and larger, but their batteries last for a considerably longer time.

Get a brand that your close friends use. That way you can borrow their lenses and trade gear if you need it. I don't care for any single brand over the others.

Personally, I shoot a Canon. I use a Canon because the firmware is so terrible. You read that right, it's terrible and that's why I got the camera.

It turns out that it's so bad that some folks hacked it and made a firmware upgrade called Magic Lantern which makes the firmware awesome. I don't need an intervalometer anymore to do time lapse videos, I can bracket up to twelve images in a sequence of my specifications.

Are you using it for Instagram and Facebook? Then you don't need a big sensor. If you're using it professionally, or intend to, then consider getting something with a larger sensor.

Your camera will not survive caving without a proper box. Buy a Pelican case. Not everyone is planning on taking their camera caving. If not, this isn't for you.


Upper Cumberland - Chocolate Lover's Wine Trail

Ruth Dyal and the excellent folks at the Upper Cumberland Tourism Association have put together a wine and chocolate tasting for this weekend; February 10, 11th & 12th, 2017.

I happen to love both wine and sweets, so this seems like a great way to get out, explore, and enjoy local delicacies. Below you'll find an interactive Google map, links to an interactive ArcMap Online map, and a static map. Feel free to use or share any of these links to help us get the word out!

Event Web Page

Event Facebook Page

ArcMap Online Interactive Map

Google Map Interactive Map


Lidar Map of Sparta, Tennessee

I wanted to make a map of my hometown of Sparta, Tennessee using the newly available lidar from the State of Tennessee. Compared with previous maps, like the USGS 1:24,000 topographic map, the new lidar data is approximately 700 times more accurate. You'll see what I mean below.

After I produced it there were just too many odd little things that were worth explaining. The first half of odd things are natural processes on the Earth that produce a specific form, or in more scientific terms, the features are of a geomorphic nature. The remainder of forms I want to share with you are human formed, or anthropogenic. 

First, let's look at the map. Your web browser likely won't let you see it in full hi-res glory (the image is 4'x3' at 300 DPI, it's big at 77 megabytes), so here is a hard link to the hi-res image.
Sparta, White County, Tennessee
Below is the stuff I thought was interesting. Feel free to follow along if you've downloaded the hi-res map.

Monteagle Limestone Boulder Field
In the north-west of the map, here are two small green colored mountains that rise around 300’ above the surrounding landscape. Look closely at the hills and you will see that they are quite rough. If you’re looking at this in real life, you’ll see a bunch of grey rocks jutting up through a thin layer of soil. This landscape should be familiar to many locals, but it’s unlikely that most have considered why it is this way.

The Monteagle limestone is our most prolific producer of caves, with 34 percent of documented caves in Tennessee being formed entirely or at least partly within this strata (TCS 2016). That’s the same reason the landscape is boulder-strewn with little to no soil. The caves exist because the rock dissolves and leaves little insoluble material behind. What remains is a thin soil that doesn’t completely cover the bedrock. This is exposed in many places across White County. I have taken to calling those areas Monteagle boulder field. Also noteworthy, but not surprising, is that there are few structures on this type of landscape.

Monteagle Limestone Sinkholes
On the eastern border of the map, at the half-way point of north and south, one can see the foothills of Dibrell Mountain, where Highway 70 winds its way up to the Cumberland Plateau. In those foothills there are large sinkholes that look like pockmarks on this map. Contrast those with the St. Louis sinkholes mentioned below. Moneagle sinkholes are more circular, and in this particular location are around 60’ deep. Some of the larger sinkholes are not exactly circular, which is likely result of two or more sinkholes combining.

St. Louis Limestone Sinkholes and the Sinkhole Plain
East of the center of the map (and in many other places), a line of shallow sinkholes runs north to south down to the Calfkiller River. Comparing these sinkholes with those of the Monteagle limestone a few things should be apparent. They tend to be less circular, some have visible drainage channels within them, and many of them have distinct swallets (looks like a steeper sinkhole inside the sinkhole). They rarely occur isolated and are more often found in large irregularly connected networks. The networks are remnants of collapsed stream caves. It also may be evident that there are few smaller surface streams on this map. This is due largely to the St. Louis limestone’s high solubility forcing streams underground.

Karst Spring
If the streams are underground, then they must surface at some point. By following Town Spring to its source you can find this location on the map. Karst springs are places where the rivers emerge. Often what they look like is a low shelf of boulders with water coming from in between them. As a caver, I would love to be able to get into all the caves behind them, but few are accessible.

Row Crop Agriculture vs Pasture and Hay
You know where Walmart is (that’s not a question). Look west from there on the other side of County Highway 1161. There you’ll find a distorted rectangular property with an interesting pattern on the soil. Those are overlapping rows, possibly where the farmer dug rows at a different direction than a previous year. Several other examples of rows can be seen if one looks closely.

Thompson Weiman Quarry
Many Spartans are familiar with this large abandoned limestone quarry, but if you need help finding it on the map, look to where Highway 70 is on the east side of the map and go a little north.

The entrance to the quarry is quite obvious on the map. For those who have been there, they will recognize the towering cliffs. For those who haven’t been there, the quarry runs underground some distance.

Abandoned Railroad
Following the obvious linear railroad bed south-west from the Thompson Weiman Quarry, one can follow what was once the route of the railroad. The line traces Nent Flatt St, turns southward at Baker St, and almost disappears until the south side of Gaines St. The railroad would have started westward, crossing South Young St and the Calfkiller River (using the same bridge as the current pedestrian walkway), and heads north towards the White County Sheriff’s Department where it would have joined a spur rail to the north which is, surprise, on Depot St. The modern rail line begins at roughly the intersection of these two historic lines.

Waste Water Treatment Plant
Almost dead center of this map is where our sewer waste goes to be treated. Two large pools can be seen.

Low head dam on the Calfkiller River
Downstream from the waste water plant, just before where Calfkiller River goes under Highway 111, there is a low head dam. Many of us have seen this as we have driven past. Have you ever wondered wh it’s there? Read on.

T & A Hydroelectric Plant
Following the north shore downstream of the previously mentioned low head dam, there is a linear feature which runs parallel to the river. This is a causeway along which water from the river was once diverted to run a powerhouse. The causeway, and much of the poured cement structure are still in place, as well as the powerhouse itself.

Clarks Mill
On Town Creek, just north of where the railroad crosses overhead, I found curious evidence of a large dam that failed. Until the creation of this map and the integration of the GNIS dataset, I had not been able to identify the structure. Looking at this map, one can now only see two lines perpendicular to the stream which represent parts of the dam structure of the mill.

Drive in Theater
Just outside the city limits of Sparta, on the north side and east of Highway 111, one can see moved earth in a radial pattern. If you’ve enjoyed watching movies at the Sparta Drive-In, then you’ll immediately recognize that those are the low rises for each successive row for cars to park in.


Making Cartographically Accurate Rivers using High Resolution Elevation Data in ArcMap

This begins as a standard stream delineation process beginning with a Digital Elevation Model (DEM). I'll work it step by step and show you what I've got so you can work alongside me. I'll be using a DEM from my part of the world, near Sparta, Tennessee. You are free to use a DEM from wherever you like. Generally, the same process applies.

I'm using the new lidar derrived 2.5' DEMs and I'm looking at a segment of the Calfkiller River for this example. I have docked the toolbar menu and expanded Spatial Analyst > Hydrology. We'll be using a bunch of commands from there. I also have raster calculator added to my menu buttons on top, that will get some use as well. All the tools we use will be on their default settings unless otherwise stated. I follow the general naming conventions provided by the tools. You may find it useful to duplicate my naming strategy until you get a feel for it.

One final note about this technique is that so far I have only used it to work on small areas. It may not be ready to by employed large scale. Also, I developed this only as a cartographic technique. While it tends to match up with water in hi resolution aerial images I'm looking at, I would certainly hesitate before applying this to more meaningful work like flood modeling.

The first thing to do is the Fill function on your DEM to smooth it out and let water flow across it in a way that makes sense to a computer (by the way, this really doesn't work well in a karst basin like the Calfkiller, as you'll see momentarily).

Once that is done, you'll run the command flow direction on the filled DEM. The flow direction output should only have numbers which are powers of 2. If you numbers which aren't, you've run flow direction on your original DEM, not the filled DEM.

When you have the flow direction, you're ready to create run flow accumulation. This will begin to develop your stream networks. If this tool takes longer than the others to run, don't worry, that is normal. When it is done, I often go into the layer's properties under the symbology tab and change the stretch type to equalize. This will let you better see the stream networks.

A few more steps and you'll be able to pull out and vectorize your stream networks. You have to make a decision about where streams begin in terms of value along your particular flow accumulation raster. There are lots of ways of going about determining this. Some of those methods are more empirical and academic than others. My method for cartography is simply eyeballing it. I use the identify tool to get the value of a pixel at a particular location, and I copy that value to the next step in Raster Calculator. What that pixel will represent is where the stream network will begin. No streams will appear upstream of it, in other words. In the picture below you can see that the expression I use is Con("FlowAcc" > 1788574,1). The odd value is where I used the identify tool to get the value of the Flow Accumulation raster at the point where I wanted the stream to begin.

Now that you've got a raster stream layer, you should convert it to a vector stream layer. Use the Stream to Feature tool as shown below.

Your streams are vectors now. In my part of the world there are lots of rivers that flow underground because of karst. I'm going to do a reality check and remove those.

Using the editor tool I've deleted all the line segments that I know aren't flowing on the surface. There, that looks better.

The next part of this workflow will require that we buffer the line slightly. We want it to be a polygon so that we can later union it with the next batch of data we produce. I'm going to buffer the line by ten feet, which is again, a completely arbitrary number. After you've worked through this once with your data, you can see how it looks and adjust that number accordingly.

Go ahead and remove Stream03, Stream02, Stream01, FlowAcc, and FlowDir from the data frame, we will no longer be needing those.

Run the Slope tool on the Fill layer, and then we want to get at the areas of the slope_fill that are less than 2%. This will help us identify where water could be pooling on the landscape. Again, my area is karst heavy, and the results of these steps will identify lots of false positives, while yours may not. See the next few pictures on how to do these steps.

Time for another reality check. Those sinkhole aren't actually lakes. I am only interested in the river channel. So we'll need to turn this into a vector layer so we can grab only what we need. The next few images will show how I do that.

Get rid of everything but Streams06 and Elev. You'll want to do a hillshade to see how the streams look against a more realistic landscape.

I think that looks pretty good. I hope that you found it helpful. If you have any tweaks, secrets, comments, or questions I'm happy to talk with you.