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WMS display the error "...image too large..." or "...InvalidDimensionalValue..."
For security reasons and for a correct sizing of the services that geoservices offer, there is a limit to the sizes of images that are generated as a result of a WMS request. The size is subject to the dimensions of the requested image (in pixels) and to the amount of geographic information to be included.
Working in a conventional screen environment (96 dpi screen resolution), and with the scale range limits defined in the geoservices, the requests that are generated do not normally produce an image that exceeds the maximum size allowed by the server.
However, it is very common for servers to show an error when a client application requests higher resolution. This happens often when printing or exporting to certain formats (e.g. PDF). This error can be shown in several ways, depending on the server and how the client application treats the messages it receives from the server. What normally happens is that the WMS layers cannot be viewed, or that the "image is too large" problem is displayed.
Solutions:
- In order to view it properly, request smaller images or with less information.
- For high resolution printing, download the files from the ICGC viewer.
Loaded layer is not displayed
Some of the services have layers with viewing limitations depending on the scale of representation. This scale is calculated according to two types of parameters:
Size of the requested image: width and height parameters.
Requested geographic extension: expressed with the two coordinates (xmin, ymin, xmax, ymax) which are specified in the BBOX parameter.
The relationship between both parameters determines the scale of the image, according to the formula below:
The visibility of a layer will depend on the fact that the specified scale is within the viewing range which has been specified by the service administrator, and which can be checked in the layer definition of each service (scale range fields) within the same document. If the requested scale does not fulfil this condition, the server will return a blank image.
Another aspect must also be taken into account. Above we calculated the desired scale by using the x coordinates (xmax and xmin), and the width of the image, but it can also be calculated with the y coordinates (ymax and ymin) and the image height:
If both formulas do not match, the image will be deformed, because the vertical and the horizontal scales will not be the same.
Read the documentation of the corresponding geoservices to know the scales of representation for each case.
Some WMS have problems with gvSIG
When accessing some WMS with gvSIG 1.12, the application comes blocked when zooming or moving the map, once the first image has been got.
This happens when the tool “Realce”, available in the menu "Propiedades del raster" is used or enabled.
It is a problem in the data processing of the service that happens with gvSIG, from version 1.9, although the tool "Realce" is only enabled by default in version 1.12.
Affected formats are JPEG, TIFF and PNG.
To avoid this problem, you have to disable the tool “Realce”:
- In the right menu, over the name of the layer, click right button and choose “Propiedades del raster”.
- Choose the "Realce" tab.
- Be sure that option “Activar” of Realce is disabled.
