Map servers and file formats
MapRequest is a Java application for assembling map images by downloading them from compatible web sites, and then saving the image along with GIS calibration information locally.
MapRequest is released under the GPL (Gnu Public License).
MapRequest downloads map information over the internet from mapping web sites running compatible software. MapRequest is pre-configured to work with a number of mapping web sites.
Note that MapRequest has no association with any mapping web site. It is up to the user to ensure that they abide by any usage agreement or copyright that the mapping web site might have.
Note that you must be a registered user on SourceForge in order to use their bug tracking system. This makes it easier for project admins to contact you regarding any questions about the bug, and also it enables you to get notified if there is any change on the bug report.
Note also that reporting a bug does not mean that the bug will necessarily be fixed.
Note that you must be a registered user on SourceForge in order to use their RFE system. This makes it easier for project admins to contact you regarding any questions about the request, and also it enables you to get notified if there is any change on the status of the request.
Note also that requesting a feature does not mean that the feature will necessarily get implemented.
When you first start MapRequest no map is selected. Click the Select Map button to bring up the list of configured map services. Double click on the name of the map you wish to use.
A layer represents a group of features that can be either displayed or not displayed on the selected map. e.g. There may be separate layers for roads and rivers.
Click the Layers button to show a list of available layers. If the check-box next to the layer name is checked, then this layer will be displayed when the next map is requested.
It may be desirable to hide some layers that are currently displayed in order to remove clutter on the map. Also it may be desirable to show a layer not currently shown in order to show the location of some feature.
To display a map, at least one layer must be selected.
For ArcIMS based maps any combination of layers can be selected, although layers not appropriate for the current level of detail may not be shown even when selected. e.g. On a topographic map, 10m contours will probably not be shown on a small map of the entire world.
For WMS based maps, some combinations of layers cannot be combined. e.g. It may not be possible to display 2 different types of satellite photo layers simultaneously. Selecting an invalid combination of layers may result in an error when requesting the map or some layers may not be shown. The behaviour depends on the map site.
Normally MapRequest displays the default view of the map using the default layers when you select the map service. WMS maps do not have the concept of default layers, so you get a warning message telling you to select one or more layers before the map can be requested. Click the Layers button and check one or more layers.
By default MapRequest uses the normal map image size used by the map web site to display maps. To request a larger map simply edit the values in the Width and Height fields and press the Request button again.
If the requested size is larger than the size normally used by the map web site then MapRequest will break the request down into multiple tiles.
Zoom in by clicking and dragging the mouse over the area on the current map that you wish to enlarge. This draws a red box on the map, and the X and Y values are updated accordingly. Click Request to request the new map.
Zoom out by clicking the Zoom Out button. This updates the X and Y values slightly. Click Request to request the new map.
A different part of the map can be displayed by zooming in or out (See “How do I zoom in/out?”) or by entering the new coordinates directly.
To enter the coordinates directly, type new values for min X, min Y, max X, and/or max Y and press the Request button. Note that the units for X and Y depend on the projection of the current map. e.g. for a latitude/longitude projection X is longitude and Y is latitude. Depending on the values typed, MapRequest may adjust some of the values slightly. (See “Why does MapRequest adjust the X and Y coordinates and image size I type?”)
Note: Y values increase from the bottom of the map to the top of the map, and X values increase from the left of the map to the right of the map. Thus min X,min Y gives the coordinates for the bottom left corner of the map, and max X,max Y gives the coordinates for the top right corner of the map.
When requesting a map, MapRequest checks that each pixel is square (i.e. an equal size using the map’s unit in both an X and Y direction) and that the image size can be broken down into multiples of the normal image size used by the remote web site. (The minimum image size is the exact size of the normal image size.)
If the values typed do not fit this exactly the following adjustments are made:
1 – The values for Width and Height are rounded up to the nearest multiple of the remote web site’s normal image size.
2 – The pixel size (for X and Y) is taken to be the X pixel size (using the original width and height), and the midpoint for X is calculated. The new values for min X and max X are calculated from the midpoint using the calculated pixel size.
3 – The midpoint for Y is calculated, and the new values for min Y and max Y are calculated from the midpoint using the calculated pixel size (from step 2).
If the width and height are not changed and values for X and Y are entered, generally this process of adjustments will result in the Y values being changed slightly.
Currently MapRequest works with ArcIMS servers and WMS servers.
Note that some mapping web sites use ArcIMS at the back end somewhere, but have a custom web front end. MapRequest will not work with these sites.
To configure MapRequest to work with a particular ArcIMS or WMS server, see the documentation on map services.
If Site X does not use ArcIMS or WMS then it will not work with the current version of MapRequest.
When writing drivers for future versions of MapRequest, the following factors are considered:
· Are there multiple sites/maps that use a similar interface? If there are only 1 or 2 sites that use the interface then there will not be enough benefit to warrant the amount of work required to write the driver.
· Are there any sites that use this interface that have a “liberal” usage agreement? If the only sites that use this interface explicitly prohibit making copies of the map in any way, shape or form, then it is unlikely that MapRequest will support this site.
For site/sites that meet these criteria, consider requesting support for this map as a new feature. See “How do I request new features in MapRequest?”
Currently MapRequest can save images in PNG (Portable Network Graphics) format and JPEG (Joint Picture Experts Group) format. JPEG (.jpg) images are good for things like satellite/aerial photographs, where as PNG (.png) images are good for other kinds of maps. When saving choose either the JPG or PNG option from the drop-down list to select the image format that MapRequest will write.
Currently MapRequest can save GIS calibration information in Ozi Explorer “.map” format.