Manually Adding Rectangles Process Question

[SCPD]

Hello, I'm sure this has been addressed but I can't seem to find it (shame on me). When I click on the plus icon to add rectangle lat/long, I only get two sets of lat/long fields. How does one draw a box / rectangle. I assume that you add another two fields and enter 4 sets of coordinates? If there is documentation on this, I haven't found it. I am getting the coordinates from google maps which is the easy part, in fact...just FYI...if someone else is trying this, just go to google maps labs and enable the latLng marker tool then save it. After this, when you right click on the map, you have the option to drop a lat/long icon box on the map which stays there until you close it. Very easy to see your city parameters with lat/long info in the dropped box.

This is the first day I am going to try this with Grand Prairie and Arlington rectangles. Otherwise, the circles are working very well, just not very precise which is a known hence the rectangle addition.

Anyway, thanks in advance.

Ken in SW Arlington.

 

[UPMan]

Two opposing corners define a rectangle (they all must be ordinally oriented). I actually had most of the area, but (aggggHHH) lost it when doing development stuff (overwrote it inadvertantly and didn't catch it until weeks later...too late to recover).

 

[SCPD]

So, for the sake of an old country boy, if...as I have, enter in four sets of coordinates, those 4 points on a map will sequentially draw a straight line to the next and the next until a box of some sort is drawn?

Is that about right?

Ken in SW Arlington

 

[UPMan]

4 points could define any 4-sided shape (not necessarily either square or rectangular).

HP-1 only accepts north/south/east/west oriented rectangles (i.e. the sides both run north/south). You define it by entering the upper left and lower right (or upper right and lower left) corner coordinates.

 

[SCPD]

Again, I am trying to visualize a 2D flat map. I thought a square or rectangle had 4 corners? Does that not mean that we need 4 separate lat/long positions? If no, how do you define a rectangle? If there are only two points used, how do you define width between the two points which are a straight line?

Sorry, but I am not a programmer or math genious or cartographer, just a simple guy. Though, I did get the GPS setup with circles working on the first attempt, fairly simple in that regard. The circles are working great with their defined areas.

Thanks again,
Ken in SW Arlington

 

[Dewey]

Again, I am trying to visualize a 2D flat map. I thought a square or rectangle had 4 corners? Does that not mean that we need 4 separate lat/long positions? If no, how do you define a rectangle? If there are only two points used, how do you define width between the two points which are a straight line?

Sorry, but I am not a programmer or math genious or cartographer, just a simple guy. Though, I did get the GPS setup with circles working on the first attempt, fairly simple in that regard. The circles are working great with their defined areas.

Thanks again,
Ken in SW Arlington

Look at it this way... take a piece of paper and put a dot in your desired upper left corner, then put another dot in your lower right corner. If you draw 90 degree north/east/west/south lines from the two dots, you will have your rectangle where the lines from the opposing dots cross (it could be a square also, but chances are it will be a rectangle).

 

[SCPD]

Well thanks, that is what I was afraid of. I don't suppose there is a app/program/website that allows one to define areas? If not, I guess we'll just have to wait until RR starts implementing rectangles or comes up with a solution to free draw a rectangle on a map.

Oh well, thought it would be a little simpler so I will just stay with cirlces until other solutions are available.

Thanks again,

Ken in SW Arlington

 

[Dewey]

It's not really as hard as it seems. In fact, it is a little easier than trying to make your own circles. Google Earth, and the other main mapping programs that I know of (Micro$oft's Streets and Trips, DeLorme's Street Atlas USA, and Garmin's BaseCamp) will give you the lat/lon of your cursor location. You just zoom out as far as needed to see the area that you want to cover, position the cursor in the virtual top left corner and note the coordinates. Now do the same thing for the lower right corner, and you have your rectangle. Trying to do the "perfect" circle requires knowing the coordinates for the exact center of the circle which is not as easy.

 

[UPMan]

Delorme (at least, probably others) lets you draw rectangles. You can then export the drawing layer and extract the opposing corners (or reimport into Excel and look at them that way. It is much easier than having to figure out 4 coordinate pairs. There are also web apps that let you draw rectangles then export the info. For example, look at:
Metrosquare

When I exported the "gpx" file for that map (gpx is a standard format for describing maps and shapes on maps), I got the below (line breakes added for clarity):

<?xml version="1.0" encoding="UTF-8"?><gpx xsi:schemaLocation="http://www.topografix.com/GPX/1/1 [url]http://www.topografix.com/GPX/1/1/gpx.xsd[/url] [url=http://www.topografix.com/GPX/Private/TopoGrafix/0/1]GPX: the GPS Exchange Format[/url] http://www.topografix.com/GPX/Private/TopoGrafix/0/1/topografix.xsd" 
creator="ScribbleMaps:http://www.scribblemaps.com/map.html?sMftdT45Kh" 
version="1.1" 
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
xmlns="http://www.topografix.com/GPX/1/1">
<trk>
<name>Scribble Rectangle</name>
<desc></desc>
<trkseg>
<trkpt lat="32.99986349466823" lon="-97.54811036997093"/>
<trkpt lat="32.58657898996735" lon="-97.54811036997093"/>
<trkpt lat="32.58657898996735" lon="-96.54011476450218"/>
<trkpt lat="32.99986349466823" lon="-96.54011476450218"/>
</trkseg>
</trk>
</gpx>

Now, as you've observed, the rectangle is being described as 4 points (each corner). However, since the rectangle is aligned north/south/east/west, you can throw out two of the corners and only keep any two diagonally opposing corners. They'll be coordinates that don't have any shared value with the other set. For example, in the above, the same rectangle can be described simply as:

<trkpt lat="32.99986349466823" lon="-97.54811036997093"/>
<trkpt lat="32.58657898996735" lon="-96.54011476450218"/>

Notice that if I had paired the first coordinate with either of the other two, either the latitude or longitude would have been the same. The HP-1 can easily determine the location of the other two corners since they will both share coordinates with the two above. To simplify data entry and reduce the amount of storage space required, you only need to enter the two corners.

For the sake of illustrating the problem with using 4 points, I drew a rectangle out by Sulphur Springs with 4 corners. As you can see, it is not anything like a rectangle. I drew another down by Gun Barrel City that, while being close to being a rectangle, would not work since it is not N/S/E/W oriented.

 

[ofd8001]

I was scratching my head on this concept too. Then all of a sudden it dawned on me that two longitude and two latitude points give you the information to create a rectangle.

Subtracting longitude point "B" from longitude point "A" gives you the WIDTH of the four sided object. (As in the east/west difference).

Subtracting latitude point "B" from latitude point "A" gives you the HEIGHT of the four sided object. (As in the north/south difference).

 

[SCPD]

So, first let me say thanks for all the responses. Hopefully, I'm not the only one learning something here.

I obtained two points on google maps then edited the screen capture in photoshop. I used the crop tool for the sake of visualization. I assume this would be a rough rectangle area with these two location points?

Thanks,
Ken in SW Arlington.

 

[UPMan]

Yep. There is another Google Maps mashup that shows city limits that might be helpful for drawing rectangles that are limited to the city boundaries:
Click for a Town/City Boundary Map

Some of the area agencies also have patrol district maps that show the limits for each. For example:
http://www.arlingtonpd.org/District/CityMap.jpg
Patrol Divisions | Fort Worth, Texas, Police Department
http://www.gptx.org/Modules/ShowDocument.aspx?documentid=1742

 

[SCPD]

Thanks, I have drawn rectangles for Grand Prairie, Arlington, Fort Worth and North Richland Hills. I will try them out tonight and this weekend. Will post results.

Ken in SW Arlington.

 

[SCPD]

Well, after a brief drive East on I-20, the rectangles I drew for Arlington and Grand Prairie seem to be working as they should. Great !!!

The next question is the following: If a user draws 10 rectangles, just to pick a number, does the increased number of rectangles for a particular system/TG degrade the performance of the HP-1 in any way? As we all know, these cities are drawn as if a 3 year old picked up a puzzle and put about 8 of the pieces together. Just look at Fort Worth if you have any doubt about this puzzle analogy. Assuming one doesn't break the city into divisions, precincts, etc.

Thanks again for all above input,
Ken in SW Arlington.

 

[SCPD]

Just to f/u after this weekend of testing around Tarrant county. Tarrant county includes Fort Worth along with many many cities including Arlington where the Cowboys and Texas Rangers play. I think I have about 22 different cities/TG's built with rectangles at this point. I have modified several of them with multiple rectangles, as many as 5 sets for one area.

Everything worked as advertised. It all was seemless, I didn't even know when one area went dark and another lit up, as it were. The only way you know is if you watch the scan and see a city being scanned all of a sudden or you start hearing a active city, like Arlington or North Richland Hills, etc.

Thanks again for the above clear answers.

By the way, Grand Prairie is by far, the cleanest trunking system I have heard. I have been monitoring trunking for a few decades around Texas. It is a Moto Type II SmartZone system. You rarely know when someone has keyed up, it is that quiet. UpMan can verify this, unreal system. It almost scares you if you're not used to it. Someone just starts talking with no static, noise...of any type.

Take care, Ken.