wmsread 3D output explanation

I can't understand the three-dimensional output of the function wmsread. I don't understand how to read it and how to connect the data it contains to latitude and longitude. (So how is the data connected to the position in the output 3D matrix?) Could someone explain it to me? Please. I have to construct a matrix with data from wmsread

Answer 1

[Tarunbir Gambhir]

The wmsread function accesses the Internet to render and retrieve a raster map from a Web Map Service (WMS) server. The function can take input of the layer which you want to retrieve, the longitude and the latitude, and the image height and width.

It gives two ouputs. the first can be a 2D greyscale or a coloured 3D image in the format : ImgHeight x ImgWidth x RGB channel. The second output is a Geographic raster reference object which ties the image to the EPSG:4326 geographic coordinate system.

For further understanding and how to use the function, I suggest you go through the examples in Mathworks Documentation.

[Chiara Zuliani]

Thank you! And how is the data contained in the RGB channel linked to the actual data?

For example, I am considering a layer containing info on population density. How is the population density of each pixel related to the RGB code corresponding to that pixel?

[Tarunbir Gambhir]

Based on my understanding, this information depends on the WMS layer you are using. A legend may be returned from the server along with the image to give you information about population density depending on the layer being used. You can go through the example on a Population Density WMS layer in this article.

Please note that the "wmsread" function relies on a stored list of servers responding in a specific way. The information returned by these servers are out on the internet and MathWorks cannot control them.