Platform: Not Platform Related
Effect of MapMarker converting the datum of all tables.
MapMarker has the ability to convert the datum of all tables it geocodes in four different ways:
- It can convert the datum of all tables to NAD83.
- It can convert the datum of all tables to NAD27.
- It can convert the datum of any table that has No Datum to NAD83.
- It can convert the datum of any table that has No Datum to NAD27.
To set this preference, go to Options>System Preferences>Datum:
What is the effect of converting the datum of a table that has already been geocoded (with the coordinates stored in the table) to a different datum?
For example, there is a NAD27 table of customers that was geocoded in a previous version of MapMarker. The coordinates were stored in Longitude and Latitude columns in the table.
It is desired to convert all of the data to NAD83 and the option "Convert all tables to NAD83" was chosen. Afterwards, additional records have been added to this NAD27 customer table that need to be geocoded.
How will the coordinates of the previously geocoded records be treated when the table's datum is changed to NAD83?
Once the table is opened and the input and output columns have been selected, the following message will be received:
"The datum of this table will be converted to NAD83. It will update every row in the table which could be a lengthy process. Proceed?"
If Yes is selected, MapMarker will go through and change the coordinates of all previously geocoded records to reflect the NAD83 datum. It will also permanently change the table's datum to NAD83, so all records geocoded in the future will have coordinates returned in NAD83.
If No is selected, the following message will be received:
"The table datum and preference datum do not match.
The datum must match before continuing.
The table will now close."
It is necessary to either change the preference in MapMarker, change the datum of the table or let MapMarker change the datum before the table will be able to be geocoded.