Overplotting of scatter points on top of coastlines

Hi all,

I am having a hard time figuring out how to plot a scatter plot on top of a worldmap without obscuring the coastlines. I have'nt used much of geoshow but I tried the following:

heat_data = load('struct.mat');
heat_data = heat_data.struct;

lat = heat_data.lat;
lon = heat_data.lon;
heat = heat_data.heat;

load coastlines
worldmap([-70,20],[-180,180])
geo = geoshow(coastlat,coastlon,"DisplayType","polygon","FaceColor",[1 1 1],'LineWidth',3);
sc = scatterm(lat,lon,75,heat,'filled','s');

sc.Children.MarkerFaceAlpha = 0.5;
sc.Children.MarkerEdgeAlpha = 0.5;
setm(gca,'FontSize',15)   % setting fontsize of lat, lon ticklabels
setm(gca,'GLineWidth',2.5)
setm(gca,'GColor','k')
set(geo,'LineWidth',3)


%%%¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤ Setting the colormap
colormap('jet')
caxis([0 20000])
col = colorbar();

As clearly seen, while doing the scatter plot on top of the worldmap, most of the coastlines of South America and the southern part of Africa are not visible. I tried to reduce the transparency of the scatter markers but still they dont seem to work. However, I am able to adjust the thickness of the grid lines which seems unaffected by the color markers, even though adjusting the thickness of the coastlines are not working!

Does anyone have a lead to circumvent this?

Thanks a lot!

Answer 1

[Cris LaPierre]

Why not reverse the plot order? Plot your scatter first, and then your coastlines on top of them?

I did have to modify some of the settings in geoshow so that the land area does not block the scatter points.

heat_data = load('struct.mat');
heat_data = heat_data.struct;

lat = heat_data.lat;
lon = heat_data.lon;
heat = heat_data.heat;

load coastlines
worldmap([-70,20],[-180,180])
sc = scatterm(lat,lon,75,heat,'filled','s');
geo = geoshow(coastlat,coastlon,'LineWidth',3,'Color','k');

sc.Children.MarkerFaceAlpha = 0.5;
sc.Children.MarkerEdgeAlpha = 0.5;
setm(gca,'FontSize',15)   % setting fontsize of lat, lon ticklabels
setm(gca,'GLineWidth',2.5)
setm(gca,'GColor','k')
set(geo,'LineWidth',3)


%%%¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤ Setting the colormap
colormap('jet')
caxis([0 20000])
col = colorbar();

[Mathan]

Hi Cris,

Wonderful. This is exactly what I was looking for. I am accepting this answer right away!

Also, what exactly do you mean when saying "I did have to modify some of the settings in geoshow so that the land area does not block the scatter points". Where exactly did you modify the settings?

P.S. Could you also guide me to any documentation which explain what the different variables such as Faleasting, Falsenorthing, FFill, Aspect, etc, etc are for the setm() that we use. There are many such properties which I do not the use and would like to learn about them.

Thanks once again.

[Cris LaPierre]

Here is your original code

geo = geoshow(coastlat,coastlon,"DisplayType","polygon","FaceColor",[1 1 1],'LineWidth',3);

Here is the updated code in my answer

geo = geoshow(coastlat,coastlon,'LineWidth',3,'Color','k');

You can find the axes-based map properties page here: https://www.mathworks.com/help/map/ref/axesm-properties.html

[Mathan]

Thanks Cris.

Answer 2

[Walter Roberson]

As well as long placing the scatterm() on the bottom, you need to watch out for the face color, because the face normally blocks view of what is behind it.

heat_data = load('struct.mat');
heat_data = heat_data.struct;

lat = heat_data.lat;
lon = heat_data.lon;
heat = heat_data.heat;

load coastlines
worldmap([-70,20],[-180,180])
sc = scatterm(lat,lon,75,heat,'filled','s');
geo = geoshow(coastlat,coastlon,"DisplayType","polygon", "FaceColor", 'none', "EdgeColor", 'k', 'LineWidth',3);

sc.Children.MarkerFaceAlpha = 0.5;
sc.Children.MarkerEdgeAlpha = 0.5;
setm(gca,'FontSize',15)   % setting fontsize of lat, lon ticklabels
setm(gca,'GLineWidth',2.5)
setm(gca,'GColor','k')
set(geo,'LineWidth',3)


%%%¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤ Setting the colormap
colormap('jet')
caxis([0 20000])
col = colorbar();

[Mathan]

Thanks Walter for the answer as well. I think I can accept only one answer but really appreciate the quick response.