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Getting Started - Things To Do Before You Begin Digitizing
Prior to digitizing you must "prepare" the following: a) your
strip charts, b) your database, and c) the pull down menus inside the
RAINDIGITIZER software program. Each of these is explained in this section.
Prepare Your Strip Charts
1. Begin with a stack of paper strip charts for a single station. The
stack should contain a complete year of strip charts if possible.
2. For each chart, carefully observe and measure the total rain depth
recorded by the plotline on the chart (this is referred to as the "eyed
rain depth" because the depth is obtained by eying the chart). Write
this value on the paper chart. Date and initial this value. Repeat this
for each chart in the stack.
3. For each chart, use the database or printed records to locate the
total daily amount of rain as measured by a daily collector gage corresponding
to this date (this is referred to as the "manual depth" because
it is measured in the field manually). Make sure the manual depth was
collected for the same time span as that of the strip chart (for example,
8 am to 8 am); if it is not, write this finding on the chart. Write the
manual depth value on the chart, and date and initial it. Repeat this
for each chart in the stack.
4. Write the following six details on each chart in the stack:
station name instrument code id start date/time
end date/time manual depth eyed rain depth
If the manual depth is unknown, leave this value blank.
5. Check the charts one-by-one for errors such as recording gaps, pen
malfunctions, inclined plotlines that occur during zero rainfall, and
others. Pay particular attention to recurring errors. These will help
determine how well and reliably the instrument is functioning and will
help determine whether any chart corrections are needed during digitizing.
Recurring errors typically result from one of a few possible sources:
charts that were misaligned (inclined) on the drum; a siphon cycle - the
mechanical emptying of a filled bucket - that drops the pen to a point
on the graph either above or below the point of zero depth; and (or) a
recurring difference between the eyed chart depth and the manual depth.
Using a pencil, note any recurring errors on each chart in the stack,
and write the corrections that will be required during the digitizing
process. As explained later, the most common instructions will be: link
two segments (needed if, because of a failure to replace the chart paper
after 24 hours, a plotline wraps around a drum more than one revolution,
thereby causing two plotlines to appear on one graph….in this case
both plotlines must be digitized and then linked); 'new segment' (used
to "join" two line segments if there is an inadvertent break
in the plotline); level a point (used to level the depth of a point to
the depth of the previous point), and 'add a comment'.
Prepare Your Database
6. Make sure that you have a "rainfall" database that contains
the tables and fields required to store rainfall-intensity data ('Create
a "rainfall" database'). A sample Microsoft Access database
called "rainfall" may be downloaded at the following link (Download
a sample "rainfall" database (MS Access) (1.6 MB Zipped....Jan
23, 2003). Note: For enhanced performance, it is recommended that you
use a SQL Server, Informix, Oracle, or similar database. Except for demonstration
purposes or small datasets, the use of an MS Access database will result
in slower performance and, in some cases, unstable operation.
7. Open your database's STATION table and enter a record for each station
for which you have rainfall strip chart data. For instructions on data
formats for specific fields and on adding data to the database refer to
the section titled 'Edit or add data
to your "rainfall" database'.
8. Open your database's INSTRUMENT table and enter a record for each
instrument for which you have data. For instructions on data formats for
specific fields and on adding data to the database refer to the section
titled 'Edit or add data to your "rainfall"
database'.
9. In order to connect your "rainfall" database to the RAIN
software you must first set the database as a 'System DSN' (Set
database as a System DSN).This will allow the program to "see"
and link to the contents of your database via "open database connectivity
(ODBC)" technology. Your database only needs to be set as a System
DSN once. If you add additional databases, you will need to set each one
as a System DSN.
Prepare (Customize) RAINDIGITIZER Pull Down Menus
10. In order to properly digitize and save your strip charts, you must
first customize the pull down and file tree menus within RAINDIGITIZER
to ensure that they include your station, instrument, Agency, Core Party,
chart, and digitizer tablet information. Specifically, you must add to
or edit the list of stations, instruments, chart types, and user names
inside the RAINDIGITIZER program. This step must be completed for each
of the stations/instruments for which you have rainfall data, and the
corresponding station_code_ids and instrument_code_ids must be identical
to those stored in your database. The program will not work unless
this step is completed.
To edit the lists, log on to RAINDIGITIZER
and click on the 'Edit Information Needed to Digitize Charts' button
under 'Program Utilities'.
The following screen will open.
This window allows you to add to, delete from, or make changes to four
lists that you routinely access when you are digitizing a chart: 1) Core
Parties, Agencies, and Stations, 2) Chart Types, 3) Comments, and 4) Users.
To add new Core Parties, Agencies, or Stations right click on any of
the existing core parties, agencies, or stations in the list. You will
see the option to Add, Edit, or Delete either a core party, agency, or
station.
The Chart Types list is used to define and set the types of strip chart
being digitized. Each Chart Type has a defined Chart Method (for example,
linear, non-linear, or tipping bucket). In addition, each Chart Type has
a defined chart height (in mm), time scale (hours per mm of chart), and
depth scale (mm of rain per mm of chart). Once a Chart Type is defined
with this Utility it remains the default type until it is changed in this
section of the program. New types can be defined by right clicking on
the chart definitions window.
The Comments list allows you to add comments that other users working
on your copy of the program (on your machine) can see and use. This can
be used to leave notes for colleagues about the settings of the program
or as a general comment to be used during digitizing.
The Users list allows you to add new users and assign passwords and appropriate
authorization levels ('Add New Users').
The following authorization levels are included: Administrator, Database
Operator, or Digitizer Technician. A Digitizer Technician can only digitize
strip charts and save them to ASCII files. A Database Operator, in addition
to digitizing charts, can add to, delete from, and edit the database,
and can work with database fields and settings. An Administrator can perform
all functions and is the only user that can add users to the system.
You must click 'Save Lists' to save any changes made before exiting
this window. Click 'Exit' to return to the main menu.
Note: You may view and edit the program settings file
if needed. The program settings are used by the RAINDIGITIZER program
to keep track of the current default settings. For example the program
remembers the settings of the COM port and digitizer tablet type so that
you do not need to reset them each time you start the program. They are
stored in a file definitions.dat file that is a plain ASCII text file.
Click 'View and Edit Program Settings File' to open this file in
notepad. You should never have to modify this file by hand, but the option
does exist.
Proceed to the next section titled 'Link
to your "rainfall" database' or return to the main
RAINDIGITIZER instructions page.
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Middle
East Rainfall Intensity