.
Digitize a Strip Chart and Save as an x,y Ascii File
on Your Hard Drive
1. Turn on your digitizer tablet and set a strip chart in place.
2. Click 'Prepare and Digitize Charts' in the 'Digitize Charts'
area of the main menu.
The following window will open.
3. Using the folder tree in the upper right part of the window, select
a target location on your hard drive that will be used to store your digitized
ascii files. Later, you will load these files from your hard drive into
the database and then convert them to meaningful time-depth rainfall data.
With the station tree in the upper left part of the window select the
station that corresponds to the strip chart(s) you will be digitizing.
Ensure that the digitizer and communications port selections are correct
in the lower right part of the window. Note: If your digitizer tablet
is unrecognized, turn its power switch off and back on again.
Ensure that the 'Default Chart Type' (the type of paper chart you are
digitizing) is set correctly in the lower right part of the window (for
example, Dynes 200).
4. Click 'Add New Chart to Staging Area'. The following screen
will appear.
Enter the appropriate start date and time, end date and time, eyed chart
depth, and manual gage depth, and click 'OK'. The 'Eyed Chart Depth'
is the total volume of rainfall plotted on the strip chart and is computed
by eye. The 'Manual Gage Depth' is the total volume of rainfall for the
date and times shown as measured by a container located at the station.
If this value is not available at the time of digitizing, leave it blank.
Return to the 'Prepare Charts and Digitizer' window, click on a selected
chart from the list, and click 'Digitize the Selected Chart'. The
following window will open.
5. If the values shown are correct, press 'Enter' on keyboard. Use the
digitizer mouse to click the bottom left and bottom right points of the
paper chart, then press 'Enter' on the keyboard. An on-screen image of
the strip chart will appear, along with a tool box containing several
buttons.
A number of tools are available in the tool box that allow you to account
for irregular plot lines and the idiosyncrasies inherent in rainfall-intensity
strip charts.
____________________________________________________________________________________________________
Tool box tools:
Return to the 'Chart Details' Window. Returns the user to the 'Chart
Details' window to allow edits to be made to the chart information such
as date, time, depth, and others.
Save to Ascii File. Saves the digitization. Clicking it will open a small
window that displays a digitization summary that demonstrates how accurately
the chart was digitized. If digitized values are outside the range of
acceptable values a label will flash a warning to alert the user to check
and, if necessary, improve the digitization. Three options are available:
change the chart's details (click 'Digitization Definitions'), redigitize
the chart (click 'Redigitize!'), or correct the current digitization (click
'Cancel'). If the chart has been digitized accurately, click 'Save Digitization'.
This will save the digitization, comments, and chart details into an ascii
file that will be automatically saved in the previously selected target
folder. For easy identification, files are automatically named according
to 'Core Party Agency-Station Name-Start Date Time'. The program will
automatically return to the 'Prepare Charts and Digitizer' window.
New Segment - Connects two line segments. This function is used to "join"
two line segments if there is a break in the plotline. Click the 'New
Segment' button after clicking on the end point of the first line segment
and before clicking the beginning point of the second line segment. After
the 'New Segment' button has been clicked, the next point digitized will
have the same time and depth values as the last point digitized, and the
two points will, in effect, be joined.
Skip Data Gap - Skips over a gap in data where data within the gap are
assumed to be unknown. Sometimes an instrument's plot pen may jump over
a portion of the chart paper causing an absence of rain-level data. Click
the 'Skip Data Gap' button before digitizing the data gap's end point.
This function will open a small window that allows the user to add a comment
describing the gap in data.
Add a Comment for a Segment - Allows a user to add a comment to the ascii
file for a selected line segment or group of line segments. Click the
button, then use the digitizer mouse to lasso the points (at least two)
between which the comment should apply. To "lasso" a segment
or group of segments, click and hold the top button of the digitizer mouse
and drag the mouse across the points of interest; release the button to
complete the lasso. A small window is displayed allowing the addition
of a comment. This comment will be included with other comments that are
added automatically by DIGITIZER for noting the special "corrections"
described in step 18. In addition, the user may click the 'View Comments'
button to view, select, or print a list of predefined comments and corresponding
comment codes.
Predefined comment codes are as follows:
Code 201 - Beginning of a new segment
202 - Alpha value added
203 - Leveled point
204 - Beginning of another sheet
205 - End of data gap
206 - End of recovered data
210 - Digitized depth factor alert
211 - Manual depth factor alert
212 - Time factor alert
213 - Extremely defective chart
Decrease Window Size - Decreases size of window by 10%.
Close Toolbox - Closes the on-screen toolbox. The toolbox may be reopened
by clicking the bottom (blue) button on the digitizer cursor.
Redigitize. This button clears the current digitization by removing all
digitized points. Clicking this button allows a user to redigitize a chart.
Zoom In - Enlarges a selected area of the screen. Clicking the button
a second time causes the screen viewing area to return to normal.
Change Chart Details - Allows user to change the information entered
for a chart in step
Level Next Point - Levels the depth of the next digitized point to the
depth of the previous point. This function typically is used for cases
in which a long time lapse occurs without rain, or when the recording
is inclined due to an instrument or paper alignment error, or when an
instrument's plot pen inadvertently drops slightly. Click the 'Level Next
Point' button before digitizing the point to be leveled. The next point
that is digitized will be "leveled" and will, in effect, have
the same value of rain depth as the point before it. Manually enter a
comment for this segment (see 'Add a Comment for a Segment' section).
Recover Data Gap - Skips over a gap in data where data within the gap
are assumed to be "known". Sometimes an instrument's plot pen
may jump over a portion of the chart paper for a known reason (for example,
the pen cannot plot due to an interference by the vertical metal strip
which holds the paper in place on the drum). Click the 'Recover Data Gap'
button before digitizing the end point of the data gap. This function
will open a small window that allows the user to add a comment describing
the gap in data.
Increase Window Size - Increases size of window by 10%.
Move Toolbox - Allows a user to move the toolbox to a different position
within the window.
____________________________________________________________________________________________________
6. Trace the chart plot line by clicking along the line at each slope
change. After digitizing the chart, click the 'Save' button on
the tool box.
This will create an ascii file and save it in your "target"
folder. The ascii file format is as follows:
RAIN2000 ASCII FILE
Core Party: Israeli
Agency: Meteorologic Service
Station Name : Haifa
Instrument Code: IM-Haifa-120200-1-D1
Digitized By:
ChartMethod: 0-Linear
Start: 06/11/55 15:00:00
End: 07/11/55 8:00:00
Digitized Time: 17
Eyed Depth: 5.1
Digitized Depth: 5.1
Selected Depth: 5.1
Manual Depth: 5.1
Number of Points: 25
Chart Reliability: 0 - Unknown
Digitation Points:
0,0,
4.8,-0.1,
5.9,2.1,
68.4,1.9,
231.3,11.4,
233.4,14,
243.3,26.6,
243.2,-50.9,CODE202
248.1,-43.4,
268.7,-37.2,
General Comment:
Digitizer Comment:
Alpha 1 : 0.07
Alpha Value Selected: None
The ascii file is now located on your hard drive. Next it should loaded
into your "rainfall" database's CHART_ASCII table.
___________________________________________________________________________________________________
To quality control the digitized ascii file(s), click the 'Quality
Control of Digitized Charts' button on the main menu.
The section titled 'Quality
Control of Digitized Charts' contains user instructions for this functionality.
___________________________________________________________________________________________________
Proceed to the next section titled 'Load
digitized ascii files to your "rainfall" database' or return
to the main RAINDIGITIZER instructions
page.
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Middle
East Rainfall Intensity