Datum used in System A / Datum used in System B

These values are used for conversions of coordinates from the pages with the A and B system from the section Parameters calculation from the main program and for conversions from inside the tables from the 3D Transformation section. The data referring to the B system ellipsoid is also used by the map projection described below in this section.

Ellipsoid short name

Set the short name of the ellipsoid. This text will be written on the labels of the tables where the ellipsoid is used.

Button Select ellipsoid ...

Select an ellipsoid from the list of predefined ellipsoids.

Semi-major axis

Set the value of the semi-major axis. The measuring unit can be changed from Options – Units Tab.

Inverse flattening

Set the value of the inverse flattening. In order to define a sphere introduce the value 0.000.

For the datum used of the B system if the selected projection works only on sphere, this box is disabled. In this case the value of the inverse flattening is considered as 0.000 (sphere) for calculating the projection and for other calculations is used the value (ellipsoid). To avoid different interpretations as sphere for projection and as ellipsoid for other calculations we recommend to choose a sphere from the list of predefined ellipsoids for the projections that are applicable only on a spheroid.

Prime Meridian

It selects the prime meridian of the used datum. If the prime meridian is different from Greenwich, then the conversion from geographic coordinates (φ, λ, h) to geocentric Cartesian coordinates (X, Y, Z) is made always with reference to the Greenwich zero meridian and for the inverse conversion the longitude calculated from (X, Y, Z) is rotated in order to return to the selected prime meridian.

Map projection used in A and B systems (on the ellipsoid ... from B system)

Select the projection that will be used for the forward or inverse conversion of the geographic coordinates (φ, λ, h) in the plane coordinates (N, E, H) from the pages with the A and B system from the Parameters calculation section from the main program and for the conversions from inside the tables from the 3D Transformation section.

Information about both the projections that can be selected and their parameters can be found at Description of the projection parameters.

Test conversion for selected map projection

It performs a conversion test of the coordinates for the selected map projection. The test can be performed for the conversion of geographic coordinates to projected coordinates and inverse.

View projection / 3D View

Set the parameters used to visualize a projection or 3D views.

Draw point with the origin of projection

Draw or not the point with the origin of projection in the visualization window. The drawn points have the name Pol.

Draw test point

Draw or not the test point in the visualization window of the projection. The drawn points have the name PntTest. The point is drawn only if it is in the representation area of the selected projection.

Draw ellipses of distortions

Draw or not the ellipses of distortions in the visualization window. These ellipses are drawn in green, the option is useful to visualize how the circles are deformed by the selected projection.

Draw continents and islands

Draw or not the continents and islands in the visualization window of the projection or in the 3D view window.

Draw countries' borders and names

Draw or not the borders and names of the countries in the visualization window of the projection or in the 3D view window.

Draw rivers and lakes

Draw or not rivers and lakes in the visualization window of the projection or in the 3D view window.

Button View projection

Open the View Projection window. In this visualization window the graphical elements will be drawn in the selected projection according to the performed settings. The visualization window can be resized, the drawing can be enlarged or reduced using the buttons from the window and by rotating the wheel of the mouse. When moving the mouse cursor the values of the plane coordinates of the projection and geographic coordinates are shown in real time.

Note: Generally, the visualization of a projection is made for the entire globe but there are particular cases when the projection is visualized only on an area, the case of the projection with local application.