Arvid - Help

Arvid is a tool for displaying spatial data. It is written in Javascript by Erik Tjong Kim Sang in the project Maps and Grammar and makes use of OpenLayers and OpenStreetMap.

Options

View

The data can be viewed in two ways: on a map and in a table. When you view data in a table, you can edit the data values by replacing them and pressing Enter.

Save File

Data that you are viewing can be saved to your own computer. Data saved in the map view will be saved in the format kml (used by Google). Data saved in the table view will be saved in the format csv (readable by Excel).

Examples

Example maps which can be inspected and saved to your own computer as examples of data files processed by Arvid.

Load file

Three file formats can be read by Arvid: csv, kml and kmz. In the kml and kmz files positions are encoded in the tag <coordinates> inside <Point> inside <Placemark>. Data values are encoded in the tag <value> inside <Data> (with a name attribute with value value) inside <ExtendedData> inside <Placemark>. In the csv files, named columns latitude and longitude express a location while the associated value is stored in the column value. Save one of the example maps to your own computer if you want to see an example of the input file format used by Arvid.

Cell size

Maximum size of each data cell measured in map degrees. A reasonable value is chosen by the software but you can choose other values if you want.

Opacity

A number indicating how transparent the cell colors are. The minimun 0 indicates complete transparency while the maximum 1 represents no transparency. The default value is 0.2.

Background map

The value on here will present a background map from OpenStreetMap. This takes extra processing time so therefore default value is off.

Combine

Indicates that cell values should be the average of n (the chosen value) neighbor cells (including themselves). This only works for numeric data values. The default value for n is 1.

Transition points

Draws a transition zone of n (the chosen number) locations. This will only work for data with exactly two values which are non-numerical. Information for chosing the transition cells is taken from the column numbers which contains pairs of distances related to the data values.

Distance

Determines a what distance (default 0) the border between two regions lies. This will only work for data with exactly two values which are non-numerical. This feature relies on the values stored in the column distance.

Below the graph and the table, the number of data points (locations) is displayed.

Below a graph there is a legend with the data values. You can change the colors assigned to the data values with the drop down menus.

Clicking on a data cell will give you its name and the associated data value. The information is displayed at the bottom left of the screen