JAVA & SuperMap

Site Admin Joined: Mar 07, 2008 Posts: 1636

From Capt Dave: On my map...clicking is NOT required. When the SST is turned on....all you have to do is stop the mouse and wait a sec and the temp will appear.

Can I do it the other way....I could but I will Not.

Here is why.

Java or JavaScript mouse over (You roll it along and the temp or whatever changes while you roll it) has 2 issues.

#1 The Lat and Long is not accurate. What it knows is the Lat and long at the corners of the image and from there it "Figures" (Fuzzy Nuts) the lat and long of the interior pixels.

If the top right is X lat and Y long and there are 400 pixels across the image and 400 pixels down the image and the bottom left is X2 lat and Y2 long then Pixel A4 must be Lat Z1 and Long Z1.

I use this exact thing to get the lat and long values for ReefCast or the Solunar Tables.

Another issue with this approach is that the earth is not flat. I can hear some people saying….that does not matter. Yes it does. 50 miles out into the stream…It matters a lot. 20 miles out it matters some. 10 miles out it still will throw you off by further than you c an find in an hour with a boat.

My map is built into a GIS system that understands things like Mercator projections and the curvature of the earth. Every pixel is registered to a location. It is very accurate anywhere inside the map. All it really cares about is it’s lat and long. We display images yes….but the “Data” we are pulling has NOTHING to do with the images. (Although they are geo-referenced and are wrapped to account for the Curvature of the earth and so on) We actually query the data for X lat and Y long and ask what is this value (Depth, Temp, Clor Level) at this location and then return the True value for that location.

#2 In Java or JavaScript the temps come from the color of the pixel. Here is how it works...Red = 70.3 Yellow = 70.1 and etc....as the mouse rolls along it counts pixels to Pixel A4, A5,B6 and then looks up to see Pixel A4 is a red pixel and it displays 70.3, when it hits a Yellow pixel it displays 70.1 and so on. With my map We could care less about the color of the pixel. All we care about is the Lat and long. Because when you stop that mouse....it "Auto Clicks" and says .....server....What is the Temp (or depth or whatever) at this lat and long on this date. There is NO fuzzy nutting. No figuring out, no nothing other than the Server replying with a query to the database what the satellite says the temp was on this day at that location.

This map was built with 20 years of offshore fishing experience and this was my second build using this technology. When given a choice about accuracy or conveyance I picked accuracy every single time.

Think about this….Lets say the SST shot’s resolution is 1 KM per pixel (most are more than that) and you are looking for a temp break 35 miles off the beach. If that image is 2 pixels off because of the curvature of the earth….you have 2 km to search for that break. If your bottom numbers where 2 kms off….would you ever find it? Sometimes it is easy to find. Sometimes you will get lucky.

I have gone to great extremes in resources to solve a lot of that and to make the products I provide as accurate as it can be done. If there was another tech out there that could do it better….I would have used it.

Posted: Sat Mar 15, 2008 9:32 am Post subject:

Very impressive, Capt!!!

Site Admin Joined: Mar 07, 2008 Posts: 226

Thank You! It has been a task....I have about 3 months in building it and at one time there were 3 of us working on it full time.

We moved the Mouse hovers last night and broke them in IE....FF still works. they should be back up in a couple hours.

Dave
_________________
Capt. Dave
Continental Shelf
Morehead City, NC
910-458-3145

Life is SHORT....Fish Hard!


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