There are two steps to using a data file to provide world coordinates for your
- Provide a description of your database file
- Connect to the appropriate file
Defining a Database File Type
dialogue box by selecting
DB description management
In this dialogue box, if you
on one of the predefined data types it will be set as your
Default Data Type
and the arrow will point to it as an indication of this.
selects that definition for
will open the
dialogue box where you will actually create your data definition.
The controls in this form are as follows:
- File Extension :
Enter the three character extension of your data file type
- Type :
A keyword to distinguish this definition from others defining files with the same
- Class :
The options here are:
- Fixed :
Generally these are downloads from survey instruments. They are ASCII files where
you have to
count the numbers of characters on each line in order to determine the values.
- Separated :
These can also be downloads of survey data but they can also be exported from
Database Management Systems (DBMS). Comma, Space and Tab are the most
- dBase :
These are the files created by the family of dBase programs. They generally have the
- Description :
A explanation of the data type to
- Filter :
To define a Filter first select whether it is for a
which compares a whole field to a value or a
which compares a part of a string. In either case you need to defined the conditions
to accept the record.
- Records to Skip :
In some files the headers may cause conflicts. To overcome this possibility you can set
of lines to be ignored before processing begins.
- Sample File :
Select a file with which to compare your definition.
- Sample Record # (status) :
This box shows one record in your selected file. Scroll through these records until you
record that is
then move on to the
- Field Descriptions :
These differ somewjat depending on the
In this example the filter is set to only accept lines that start with "08TP" and each value
is determined by counting the characters from the left. Thus the point number starts at
position 4 and is 4 digits long, the X coordinate starts at position 8 and is 10 digits
(including the decimal)
This example is a CSV file exported from a spreadsheet program in which the separator
is a Comma and there are no quotations around the text. The first field is the point
number, the second the X coordinate, etc.
For dBase files the fields have names and no filters are required. The boxes will show a
list of the available fields for that database and selecting one will show the value in the
right hand box. If the field selected does not contain numeric data the value box will be
Connecting to a Data File
Once your database is configured you need to use the
dialogue box to connect your database to the image. To access this dialogue box
icon from the main menu or select the
button on the
dialogue box, which you get when you select a point.
Once you have the dialogue box above, select the predefined type from the list of
Database File Definitions you have prepared
and then, to attach a data file by clicking the File Open
button and browsing for the data file containing the coordinates for the current image
When a data file is selected the first 3 lines will be displayed in the sample window so
you can browse it to insure that you are connected to the correct file or to find the
point number you are looking for.
Henceforth the values in these fields, for the point number being identified,
will be offered as the default for the
World Coordinate Points
for each point selected.
Occasionally it happens that your field notes become out of sync with your recording.
Adjust database points
field addresses this possibility by allowing you to adjust all point numbers up or down a
few to see if this is the case when you get severely distorted results.
The other cause of really bad results is being connected to the wrong database.
When you select
you will be asked if you want to
update all points
with the values in the selected database.
Generated by: CART
(Thu Sep 20 17:56:53 2007