How to plot a contour map in UTM projection?

Question

Tanvi Gupta 2015-9-10

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https://ww2.mathworks.cn/matlabcentral/answers/241857-how-to-plot-a-contour-map-in-utm-projection

编辑： Tanvi Gupta 2015-9-11

I am trying to plot data over a regular grid(GRID_VEL50 corresponding to Northings and Eastings in meters-UTM map projection) in the form of filled contours. I want the corresponding map overlayed along with it. Following are the variables used in the code: GRID_VEL50 (dim:156X150),GRID_X (Eastings,dim:150) and GRID_Y (Northings,dim:156). Here is the script, I tried for plotting the same:

    axesm('tranmerc','MapLatLimit',[7 37.5],'MapLonLimit',[66.667 98.6666717529297]); 
    framem; gridm; axis off; tightmap;
    x11 =245895.96;  %meter, the North-West corner(66.667 deg in long)
    y11 =774370.68;  %meter, the North-West corner(7 deg in lat) 
    dx1 = 25000;     %in meter
    dy1 =-25000;     %in meter
    R=makerefmat(x11, y11, dx1, dy1);
    contourfm(GRID_VEL50,R,'r','LineWidth',0.0001)
    coast = load('coast');
    geoshow(coast.lat, coast.long, 'Color', 'black')
    contourcbar

On running this script, it gives an error, stating :"Error using constructGeoRasterReference (line 45)." The referencing array comes out to be a 3X2 array as mentioned in help documentation.

R =
                           0                    -25000
                       25000                         0
                   220895.96                 799370.68

I am unable to debug this. Is there any other method to plot contours in a specific map projection?

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Walter Roberson 2015-9-10

You indicate lat 7 long 66.667 as your North-West corner, but your axesm latitudes are from 7 to 37.5 which implies that lat 7 is to be a South corner rather than a North corner. Please re-check which points are the North or South extremes and please check the sign of your dx1 and dy1 .

When I calculate with the dx1 and dy1 values you give, I do not as yet see any reason why the latitude would exceed +90 to -90, but I do see that it would be outside your map axes which suggests you have incorrect bounds or incorrect signs.

Tanvi Gupta 2015-9-11

编辑：Tanvi Gupta 2015-9-11

在 MATLAB Online 中打开

Rightly pointed. I changed y11 and gave the run. Still, same error message is coming.

y11 =4152898; % the upper left corner(37.5 deg in lat)

I am converting lat(37.5 N) and long(66.667) to utm coordinate points to get x11 and y11.

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Answer 1

Walter Roberson 2015-9-11

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https://ww2.mathworks.cn/matlabcentral/answers/241857-how-to-plot-a-contour-map-in-utm-projection#answer_191992

在 MATLAB Online 中打开

In the documentation it is not clear to me how makerefmat distinguishes between the x/y case and the long/lat case. I speculate that if you pass integral numbers that it might interpret them as x/y, so try with

R=makerefmat(round(x11), round(y11), round(dx1), round(dy1));

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Tanvi Gupta 2015-9-11

编辑：Tanvi Gupta 2015-9-11

Tried with integral numbers. It still shows the same error. I am using the example given on following link for making referencing array: http://in.mathworks.com/help/map/ref/makerefmat.html

If I use a referencing vector [cells/deg,North lat,West lon], e.g.[4,37.5,66.667] contours with map overlayed are generated. But I know this is not correct because it gives a wrong spread of variable over the map.

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