Displaying Lat/Lon and Other Grids

Lat/Lon Grid

The lat/lon grid can be displayed for any map of any scale of any projection. There are some limitations, such as maps crossing the 180 degree longitude and maps which have a border outside a valid lat/lon such as the example world map.

Other Grid

The grid displayed is the one selected in the "Alternate Grid" in configuration. If the UTM grid is selected then the grid displayed on the map is a UTM grid etc.

The display of a grid is very much controlled by the map. It is really only intended for maps of scale say 1:250,000 and below, maps cannot cross a zone boundary (the part displayed on screen anyway). As an example you cannot expect a grid to be displayed on a map which covers a country or the whole world. This does not apply to the UK OSGB (BNG) or the Irish Grid as the format of these grids allow them to be handled as a special case.

I am sure you will find there will be times when the grid will not be displayed on a map.

Parameters

Most of the parameters need no explanation, the ones which are not obvious are decribed below.

Clip to Neat Line - If checked the grid will stop at the neat line boundary which is setup using the corner markers in map calibration. For maps with curved projections odd displays can be noticed if "clip to neat line" is active but these are unimportant.

Auto Scale - If checked as you zoom the map in and out the "Line Interval" will be automatically altered to keep roughly the same line spacing on the display. The line spacing however must be one of the accepted values in the Line Interval selection box.

Numbers

• Normal - Grid numbers are displayed in full.
• No Meters - If checked the Grid (on the map grid) will be displayed without the meters - example 1273000 can now display as 1273. This only applies if the last 3 digits of the grid are 000, if they are not the grid number is displayed in full.
• Last 3 Digits - Only the last 3 digits are displayed if they are not 000, if the grid number is an even multiple of 1000 (last 3 digits are 000) then it is displayed as example - 243* where the full number would be 243000. The * indicates the this is a full grid number without the 000. This lets you work out the full coordinate number. Example - If the number of the next grid line is 200 then the full grid number would be 243200.

Save - Will save you current settings in the the map file and they become the default for the map.

Label Screen Display - "Only on Map borders" the labels will only be shown on the edge of the map. "On all Screens" the labels will be seen on all screens.

Default - Saves the current settings as the defaults to be used when ever the Grid Config dialog is displayed for a map where a grid is not already configured the defaults will be entered automatically (if you have saved defaults), all you have to do is turn the grid on.

Notes

Printing - A grid will be printed if it is displayed on screen at the time of printing.

Limitations

There is a limit of 200 lines for each grid which can be displayed, after this the lines stop. This is to prevent delays in regaining control (if ever) if too fine a grid is chosen. 200 lines on a screen still allows a very fine grid to be used.

There is a limit of 50 labels which can be used on the grid screen display. When this limit is exceeded the labels will stop being displayed. This limit is not restricting as even with 50 the labels overlay each other anyway and cannot be read.