ocean current velocity data m_quiver plot on high resolution coast line refreshdata not working

Question

Jon Rendulic 2015-12-21

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/261147-ocean-current-velocity-data-m_quiver-plot-on-high-resolution-coast-line-refreshdata-not-working

评论： Walter Roberson 2017-2-12

I have u & v ocean current forecast velocity data and I need to plot every three hours in a loop using 8 days worth of data, then use this plot to create an animated gif. If I loop the map projection its very slow but works. So I was hoping to only refresh the plot data but refreshdata is either not working or more likely than not, I am not using it correctly. Could someone please review my code and see what I am doing wrong or please point me in the right direction. I updated my code with the suggestion below and was still unable to get it to work

This animated gif below is what I am aiming to accomplish with some more efficient code. Right now its super slow because it loops the code that creates the map and axis with the high resolution coastline (the coastline slows this down significantly) and m_quiver plot each iteration.

get_vel_data
global start_stamp
global tstamp
t = datenum(DateTime, 'yyyy-mm-ddTHH:MM:SSZ');
t = datetime(t,'ConvertFrom','datenum','Format', 'yyyy-MM-dd HH:mm:ss');
% start = '2015-11-14 00:00:00';
start = datetime('2015-12-01 00:00:00', 'Format', 'yyyy-MM-dd HH:mm:ss');
start_stamp = datestr(start);
ds = dataset(t,Lat,Lon,u_vel,v_vel);
%%Animated Plot
figure(99)
filename = 'testnew72.gif';
% set map and grid
axes('Position',[0.1,0.1,0.8,0.8]);
m_proj('albers equal-area','lat',[50 65],'lon',[185 215]);
m_gshhs_h('patch',[.6 .6 .6]);
m_grid('linest','none','linewidth',2,'tickdir','out','xaxisloc','top','yaxisloc','right');
tiHan = title(['U and V Ocean Current Velocity Forecast Data Downloaded on ',start_stamp], 'Interpreter', 'none','FontWeight','bold','FontSize',8);
% axis x, y value of title position
tiPos = get (tiHan, 'position'); 
xyrange = axis;
% move title up
set(tiHan, 'position', tiPos + [0 0.05 * (xyrange(4) - xyrange(3)) 0]); 
% so Title doesn't move on zoom.
set(tiHan, 'units', 'inches');
xlabel(['Forecast Data for ',tstamp], 'Interpreter', 'none','FontWeight','bold','FontSize',8);
hold on;
lat = 0;
lon = 0;
u = 0;
v = 0;
uv_plot = m_quiver(lon,lat,u,v);
% looping through the 64 different time frames.  24hrs/(3hr fcasts)*8days=64
for n = 1:64
      if n==1;
          i=0;
      else 
      i=i+3;
      end
      % update timestamp for axis label
      tstamp = start + hours(i);
      tstamp = datestr(tstamp);
%      uv_plot.UDataSource = 'u';
%      uv_plot.VDataSource = 'v';
%      uv_plot.XDataSource = 'lat';
%      uv_plot.YDataSource = 'lon';
%     xlabel([], 'Interpreter', 'none','FontWeight','bold','FontSize',8);
      % update temp dataset 
      t0 = ds(ds.t == start + hours(i),{'t','Lat','Lon','u_vel','v_vel'});
      lat = t0.Lat;
      lon = t0.Lon;
      u = t0.u_vel;
      v = t0.v_vel;
      uv_plot.UData = 'u';
      uv_plot.VData = 'v';
      uv_plot.XData = 'lat';
      uv_plot.YData = 'lon';
      drawnow()
      xlabel(['Forecast Data for ',tstamp], 'Interpreter', 'none','FontWeight','bold','FontSize',8);
      % clf;
        frame = getframe(99);
        im = frame2im(frame);
        [imind,cm] = rgb2ind(im,256);
        if n == 1;
            imwrite(imind,cm,filename,'gif', 'Loopcount',inf);
        else
            imwrite(imind,cm,filename,'gif','WriteMode','append');
        end
  end

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Answer 1

Walter Roberson 2015-12-21

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https://ww2.mathworks.cn/matlabcentral/answers/261147-ocean-current-velocity-data-m_quiver-plot-on-high-resolution-coast-line-refreshdata-not-working#answer_203875

在 MATLAB Online 中打开

Instead of refreshdata() in the loop, use

      t0 = ds(ds.t == start + hours(i),{'t','Lat','Lon','u_vel','v_vel'});
      lat = t0.Lat;
      lon = t0.Lon;
      u = t0.u_vel;
      v = t0.v_vel;
       uv_plot.UData = U;
       uv_plot.VData = v;
       uv_plot.XData = lat;
       uv_plot.YData = lon;

and the drawnow() will do the update.

refreshdata() is slower than setting the parameters to their desired values.

You also do not need the

xlabel([], 'Interpreter', 'none','FontWeight','bold','FontSize',8);

as you change the xlabel again a few lines later.

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Jon Rendulic 2016-1-10

I made the change and it still does not draw the vectors.

Keep in mind that this code originally worked hence the animated gif. It runs fine in a loop but is extremely slow.

The reason I made this post and decided to try using drawnow or refreshdata was to make my code more efficient. I was looking for a smarter way to solve this problem.

Jon Rendulic 2016-1-10

在 MATLAB Online 中打开

This is the code that I have that works but is extremely slow.

get_vel_data
global start_stamp
global tstamp
t = datenum(DateTime, 'yyyy-mm-ddTHH:MM:SSZ');
t = datetime(t,'ConvertFrom','datenum','Format', 'yyyy-MM-dd HH:mm:ss');
% start = '2015-11-14 00:00:00';
start = datetime('2015-12-01 00:00:00', 'Format', 'yyyy-MM-dd HH:mm:ss');
start_stamp = datestr(start);
ds = dataset(t,Lat,Lon,u_vel,v_vel);
%%Animated Plot
figure(99)
filename = 'testnew99.gif';
% set map and grid
% looping through the 64 different time frames.  24hrs/(3hr fcasts)*8days=64
for n = 1:64
    if n==1;
        i=0;
    else 
    i=i+3;
    end
      % update timestamp for axis label
      tstamp = start + hours(i);
      tstamp = datestr(tstamp);
      % update temp dataset 
      t0 = ds(ds.t == start + hours(i),{'t','Lat','Lon','u_vel','v_vel'});
      lat0 = t0.Lat; lon0 = t0.Lon;
      u0 = t0.u_vel; v0 = t0.v_vel;
      clf;
      v_plot(lat0,lon0,u0,v0)
%      pause(.05);
        drawnow
        frame = getframe(99);
        im = frame2im(frame);
        [imind,cm] = rgb2ind(im,256);
        if n == 1;
            imwrite(imind,cm,filename,'gif', 'Loopcount',inf);
        else
            imwrite(imind,cm,filename,'gif','WriteMode','append');
        end
  end

The code for v_plot is:

function v_plot(lat0, lon0, u0, v0)

global start_stamp
global tstamp
axes('Position',[0.1,0.1,0.8,0.8]);
m_proj('albers equal-area','lat',[55 60],'lon',[200 210]);
m_gshhs_h('patch',[.6 .6 .6]);
m_grid('linest','none','linewidth',2,'tickdir','out','xaxisloc','top','yaxisloc','right');
tiHan = title(['U and V Ocean Current Velocity Forecast Data Downloaded on ',start_stamp], 'Interpreter', 'none','FontWeight','bold','FontSize',8);
tiPos = get (tiHan, 'position'); % axis x, y value of title position
xyrange = axis;
set(tiHan, 'position', tiPos + [0 0.05 * (xyrange(4) - xyrange(3)) 0]); % move title up
set(tiHan, 'units', 'inches'); % so Title doesn't move on zoom.
xlabel(['Forecast Data for ',tstamp], 'Interpreter', 'none','FontWeight','bold','FontSize',8);
hold on;
m_quiver(lon0,lat0,u0,v0);

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Answer 2

Kyon 2017-2-12

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/261147-ocean-current-velocity-data-m_quiver-plot-on-high-resolution-coast-line-refreshdata-not-working#answer_254396

i want to do the map in 3d

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Walter Roberson 2017-2-12

What map do you want to do in 3D?

And do you have the Mapping Toolbox?

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ocean current velocity data m_quiver plot on high resolution coast line refreshdata not working

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ocean current velocity data m_quiver plot on high resolution coast line refreshdata not working

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