This video illustrates the use of the Distance Bearing tool.

The distance bearing tool in the D2D perspective, as its name implies, calculates the distance and compass bearing between two particular points. 
 
Since landmarks are important in this exercise, let’s load a procedure which prepopulates our view with cities and also sets useful display characteristics like magnification. We can hit CTRL-O on our keyboard to open the GUI for loading procedures. From the OUN group, we’ll select W2B_Exercises, at the bottom… double click that. And then from the window which appears, we’ll double click on the first and only procedure. We’ll close this. 
And we can see that our display now has a yellow cities map, and also is preconfigured to have a higher magnification for text visibility, and a higher frame rate which is useful for looking at data. We’ll actually go and lower the magnification slightly to 1.5. Let’s finally also confirm that our CAVE clock is set correctly to 23:40Z on May 31, 2013 as it should be for all Fundamentals lessons.

OK, now let’s get on to the distance bearing tool. From the tools menu, select “Distance Bearing.” Now, you’ll see the tool added to the product legend at the bottom right. We want to confirm that it says “Editable” in this legend entry. If not, then we can use the middle mouse button – the scroll wheel – to click on it and toggle it from un-editable to editable.  Note that by right clicking and holding on the legend entry you can also change the editability by selecting this item, if it’s not already checked. Note that if the distance bearing lines are editable, you should see circles at the endpoints of each line.

The distance bearing tool consists of six lines (very similar to baselines) with one end of each labeled with the distance spanned in miles and the azimuth in degrees relative to the unlabeled end. When using this tool, think of the unlabeled end as the origin, and the labeled end as the destination.

Let’s jump into an example. Let’s load some KCRI data by going to the top menu, and selecting the first item on the list, “0.5 Z+SRM8.” Now, we’ll hit the period button on the keyboard twice to toggle to storm relative motion, which is our product of choice for this exercise. And we’ll use the mouse scroll wheel to zoom in to the velocity couplet that we see on the screen, which is just southeast of El Reno.

Now, even with our city names colored yellow to stand out, it’s a little hard to see against the radar data. So let’s use a really handy feature of AWIPS2 for adjusting the brightness of our display data. Now, you can load this either by going to the radar items in the product legend, and long right-clicking, and choosing the imaging item from the menu which appears.  Or, more simply, hit CTRL-I on your keyboard and this brings up the imaging GUI. Now, there’s a lot going on here but we’re going to focus just on this slider here labeled “brightness.” Click and drag the slider down to a value of approximately 50%, and as you do so you can see the brightness of our radar data being reduced in the background.  We’ll close out of this imaging GUI now. Clearly, the map features, and – if I zoom out –the distance bearing lines have much better visibility now against our radar data, having lowered the brightness.

So let’s present a scenario where we might use distance bearing. At 23:40Z a caller from Yukon calls and wants to know their distance from the tornado and whether it will hit them. Let’s scroll in a little more with the mouse wheel.  Now, when it’s first loaded… actually, we may have to zoom out to see the distance bearing lines.  And, once we can see both end points, let’s just click and drag each endpoint to roughly the vicinity of our scenario.  We’ll fine tune this in a moment after we zoom in.  Note also that you can move entire distance bearing lines by clicking and dragging somewhere in the middle between the endpoints.

So, we’ll zoom back in now, and here’s where we’ll fine tune our distance bearing lines a little bit.  Since we want to use our tornado as our reference in this case, let’s grab the unlabeled end of the distance bearing line and place that over the couplet. And we’ll take the labeled endpoint of the distance bearing line, and click and drag that with the left mouse button over to Yukon.

Now, you should see as I do that Yukon is at a distance of 6 miles from the tornado. The distance bearing tool can’t actually tell us if the tornado is going to hit, but by advancing back and forth a few frames we can see the couplet has an eastward motion. Now, we can easily see that Yukon is east of the couplet, but the azimuth label on the distance bearing tool confirms the Yukon is at a bearing of approximately 91 degrees, or east, of the tornado. This will certainly cause us some concern for that town.

While we’re speaking with this caller, we should also point out a second tornado, southeast of our original one, with anticyclonic motion suggested by inbound flow to the northeast of outbound flow. Now, stepping back and forth in the frames with our left and right arrows again, we see some erratic motion with this couplet but an overall southeast motion developing.

On our most recent radar data, we can move the unlabeled endpoint from our first couplet, by clicking and dragging with the left mouse button, to the new couplet. And now we can provide information to our caller about this second hazard as well. As the updated information suggests, our caller from Yukon is 4 miles away from this second tornado, which is concerning, although Yukon is at a bearing of 51 degrees from the tornado (or northeast).  Now, given the southeast vector of the anticyclonic couplet, this northeast position may reduce the vulnerability of Yukon to this second threat.

So, in summary, when using distance bearing lines, remember that the labeled end of the distance bearing line provides information relative to the unlabeled end. Now, we’ve seen using the tornado as a reference or “origin” and directly reading off the information displayed by the tool that the caller is northeast of this second couplet. Intuitively, we should be able to easily translate that information into information about where the tornado is relative to the caller (obviously it’s southwest), but you can also swap the endpoints of the distance bearing line… placing the labeled end over the couplet, and the unlabeled or “reference” end over the caller.  And this tells you that the tornado is at a bearing of 233 degrees (or, southwest, as expected) from the caller.

So in summary, if you need a distance or bearing from anything in D2D, you can use the distance bearing tool. This can be a great way to get accurate position information, which may be especially useful in map areas where distances are less familiar to you, or when cardinal directions don’t necessarily orient as expected, such as in certain map projections. 

When you’re through with the tool, as with any loaded product, you can toggle its visibility by left-clicking on the item in the product legend, or you can completely unload it by long right-clicking and selecting “unload.”