Tutorial: Register Image and Digitize
Caveats on image registration.
WW2 situation maps from http://memory.loc.gov/ammem/collections/maps/wwii/date.html
This page has an overview of the process. Details are on the pages linked to from the overview.
Download JPEG2000 file
for desired date.
Pick 50% or 100% zoom level. The 50% level should have an acceptable lowering of the image quality, and will require 25% of the file storage. Verify that you can read the map at this resolution; if not, go with the 100%.
Save image with PNG format. Rename as "SIT-MAP_DDMMM194Y". This file is unregistered, and cannot be used for mapping.
Close map, and do not use it any further.
Open New image with PNG file you just saved.
Register image using map graticule for quadrangle registration. This will create two databases, one with the registration points and another with the triangle mappings. The triangle mappings can always be regenerated.
|Original map downloaded from the Library of Congress. Note conical projection with both parallels and meridians curved,
removed secret classification, marginal information, and in
the lower right that this map entered the Library of Congress
collections in November 1944, three months after the day depicted.
If the map edges are not parallels and meridians, you can extrapolate to the edges (or the margins if you want to retain that information).
Because this map spans the Prime Meridian, you must be very careful as you enter the longitude values.
|Export map to Google Earth
from the Registration window, using Reg File, export map to Google
If it does not line up, carefully look at which part of the map appears to be in error, and then redo the Delaunay triangulation registration paying particular attention to the graphs provided and the triangulation overlay. Adjust the registration.
|Reprojected map after
Delaunay triangulation registration. Note the decollaring which removed the marginal
information, and straightened the meridians and parallels.
Select Register button, and then Reproject map. This will close the map registration and open the registered map for use in MICRODEM.
This map can be viewed in the main map window, and used for all program operations.
|Digitize locations of all divisions on the map. Divisions have
an "XX" above the box for the symbol. Name this
file "DIVISIONS_xxMonth1944". You have two options:
You must carefully consider how to define the database table. Follow the conventions in the database shown on the right. Some software might limit the length of the NAME field, so you might want to abbreviate the division identifiers.
As a point geometry, this database is very tolerant of mistakes as it resides in a single DBF file. You can edit the file in MICRODEM, or in Excel (export via CSV back to MICRODEM).
Create and fill an icon field, and populate it with the correct symbols for each type of division. Use the Add from substring flag option and make new fields for "GER", "US", "BRIT", "ARM", and "INF". You can then filter for US='Y' and ARM='Y', and do a Fill field for all records on the ICON fields and put in "us-Arm-Div.gif".
Add a DATE field on the Edit option, Insert new field and then fill all values with a single command (Fill field for all records) since all the divisions entered should be for a single day. This will allow us to merge all the daily databases, and filter on the date.
Icons are for Infantry, Armor, and Airborne divisions for the US (dark blue), UK and other allies (cyan), and Germany (red). Blue/Red is standard military symbology.
|Digitize the front lines on the map. Name this file
"FRONT_LINES_xxJuxx1944". You have two options:
As a line geometry, this will be fussy and you must keep all three parts of the shapefile together.
|Map in Google Earth after digitizing unit locations and front lines. This shows the default push pins and not unit icons that must be added in MICRODEM, and which can then be exported back to Google Earth.|
|Databases displayed on
SRTM Map using Database
overlay option. To get icons, change
Plotting Options for the database. You can adjust the size of
the icons with the scaling factor.
Export the front lines and the division locations from the Report: button on the table display forms.
Clean up KML exports within Google Earth
Label the points and plot your registration points. Look at the four corners. If they are not in the correct locations, fix them by editing in the grid. Then you can retry the registration after closing the map and deleting the files listed above.
Example 2: using affine transformation.
Last revision 2/28/2014