The lowest branch in the QV X-Plorer tree window you will find the System folder. Here you have access to different databases in which system parameters are managed:
These include the database Grids_Datums which is write-protected and which includes all predefined map datums and grids. Here you find all parameters which define a given map datum or a given map grid.
Following, you find two databases for map datums and grids which you might wish to define yourself. One is named My Grids Datums DEMs and has read and write access, the other one is named My_Grids_Datums_DEMs and is write-protected.
You can add, modify or delete a map datum or a grid. Furthermore, digital elevation models (DEMs) can be imported, deleted and activated (see below).
Finally you find another write-protected database where all names and ephemeris parammeters of starts and planets are stored.
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Right-click on the table Datums in the My Grids Datums DEMs database. You can then choose New for creating a new map datum or Duplicate for copying and modifying an existing one.
In the same pull-down menu you will also finde the options rename, delete, cut or copy.
For creating a new map datum proceed as follows:
Right-click on the table Grids in the My Grids Datums DEMs database. You can then choose New for creating a new map datum or Duplicate for copying and modifying an existing one.
In the same pull-down menu you will also finde the options rename, delete, cut or copy.
For creating a new map grid proceed as follows:
User-defined grids and map datums are saved in the file user.qbd. Furthermore, the parameters for every map that uses a specific datum/grid are saved along with the calibration information.
That means that you can transfer the map with the calibration file to another PC with QV. When opening the map on another computer for the first time, the new datum/grid will automatically be added to the user.qdb file.
Even if you delete your own datum/grid by accident and later on open a map with a calibration file based on this definition, QV will automatically add the datum/grid to the user.qdb file and the map will be opened correctly.
A digital elevation model (DEM) is a file in which the terrain elevation for a specific area is stored as a 3D matrix. Similar to a digital map, a DEM has a specific resolution and must be calibrated, i.e. there are specific rules on how to extract the corresponding altitude for a given geographic coordinate.
QV can read DEMs and thus specify altitude values for any coordinate. Thus you can calculate an altitude profile for a planned tour, add altitude information to existing GPS data and create a three-dimensional picture of the landscape. So, for a 3D-view of a map (and the other functions mentioned), a DEM is an obligate requirement. Technically, the 3D-modelling is done through a triangular irregular network (TIN), so the earth surface is represented by a network of triangels. When displaying a map in 3D, the resolution of this TIN can be adjusted using the 3D elevation options (see chapter Map window).
There are various Digital Elevation Models availablle on the market which differ in resolution and absolute accuracy of the altitude values.
Here is a list of what we offer ready-to-use for QuoVadis 6:
Important Remark: Please note that DEMs which come with third party suppliers of topographic maps usually cannot be imported into QV due to copyright restrictions!
Beware that there are several reference systems available for elevation values. Various standards have been established so the average sealevel is only one reference but not the unique standard! Other systems refer to various earth spheroids like WGS 84. If you require an absolute accuracy within a few meters, it is essential to consider the elevation reference system!