Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!uwmcsd1!len
From: len@csd1.milw.wisc.edu (Leonard P Levine)
Newsgroups: comp.graphics
Subject: Re: World map
Message-ID: <6870@uwmcsd1.UUCP>
Date: 24 Sep 88 17:28:04 GMT
References: <1197@cleo.SW.MCC.COM>
Sender: daemon@uwmcsd1.UUCP
Lines: 246
On September 13th James Peterson posted a map of the North Ameri-
can Continent (noted here as the NAC) that was quite a neat job.
I worked it over and examined areas of the map that I have an
interest in and found some problems. This is not a flame about
wasted transmission time, etc., but is a note about the accuracy
of the data submitted.
I have compared those data with data taken from the US Map data
disk (disk RD 9.0 from Public Brand Software, 1-800-426-DISK) and
have noted that the data for the states of Wisconsin-Michigan-
Indiana-Illinois, which together form the boundary of Lake Michi-
gan give a quite different shape to the lake than does the NAC
data set.
The difference is fairly large and is not just traceable to a few
wild points. I include below the data for the arm of Lake Michi-
gan called Green Bay as an example, although the data is equally
bad in other areas. As a single example, I have found the loca-
tion of the city of Green Bay on the two data sets (that point is
located on the data sets below) and find it to be (-88.0262,
44.5256) on the RD 9.0 disk and at (-88.116, 44.331) on the NAC
data set. The difference is 14.16 miles, well outside of the
apparent tolerances of the two data sets. Finally, the RD 9.0
data set agrees very well with the published maps of the states
that I have studied. The precision of these state maps is clear-
ly better than 2 or 3 miles.
Finally, although I have not seen them, disks RD 6.0, RD 7.0 and
RD 8.0 from Public Brand Software are a world data set that, from
its description, seems to be the same data as was submitted by
Mr. Peterson. Nowhere in my copy of disk RD 9.0 is there any
indication of authorship or claim of copywrite.
Does any of this matter? In my judgment, if we are interested in
pretty pictures, then we can accept anything that gives such
pictures. If we want maps that matter, we better look more
closely.
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| Leonard P. Levine e-mail len@evax.milw.wisc.edu |
| Professor, Computer Science Office (414) 229-5170 |
| University of Wisconsin-Milwaukee Home (414) 962-4719 |
| Milwaukee, WI 53201 U.S.A. Modem (414) 962-6228 |
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The RD 9.0 data for Wisconsin - Green Bay Area:
-88.0084 45.7882 -87.9799 45.7722
-87.9799 45.7722 -87.9026 45.7584
-87.9026 45.7584 -87.8380 45.7204
-87.8380 45.7204 -87.8051 45.6892
-87.8051 45.6892 -87.8114 45.6743
-87.8114 45.6743 -87.8393 45.6601
-87.8393 45.6601 -87.8193 45.6387
-87.8193 45.6387 -87.8048 45.6137
-87.8048 45.6137 -87.8122 45.5857
-87.8122 45.5857 -87.8378 45.5640
-87.8378 45.5640 -87.8266 45.5316
-87.8266 45.5316 -87.8236 45.4957
-87.8236 45.4957 -87.8535 45.4514
-87.8535 45.4514 -87.8753 45.4051
-87.8753 45.4051 -87.8960 45.3756
-87.8960 45.3756 -87.8657 45.3501
-87.8657 45.3501 -87.8336 45.3490
-87.8336 45.3490 -87.7439 45.3686
-87.7439 45.3686 -87.6976 45.3802
-87.6976 45.3802 -87.6732 45.3473
-87.6732 45.3473 -87.6952 45.2991
-87.6952 45.2991 -87.7366 45.2422
-87.7366 45.2422 -87.7499 45.2050
-87.7499 45.2050 -87.7461 45.1822
-87.7461 45.1822 -87.7000 45.1543
-87.7000 45.1543 -87.6677 45.1192
-87.6677 45.1192 -87.6258 45.1083
-87.6258 45.1083 -87.5919 45.0977
-87.5919 45.0977 -87.6102 45.0664
-87.6102 45.0664 -87.6171 45.0045
-87.6171 45.0045 -87.6340 44.9919
-87.6340 44.9919 -87.7255 44.9782
-87.7255 44.9782 -87.7615 44.9587
-87.7615 44.9587 -87.7969 44.9468
-87.7969 44.9468 -87.8148 44.9173
-87.8148 44.9173 -87.8224 44.8837
-87.8224 44.8837 -87.8512 44.8508
-87.8512 44.8508 -87.8872 44.8275
-87.8872 44.8275 -87.9121 44.8133
-87.9121 44.8133 -87.9201 44.7722
-87.9201 44.7722 -87.9787 44.7290
-87.9787 44.7290 -87.9803 44.7027
-87.9803 44.7027 -87.9848 44.6746
-87.9848 44.6746 -88.0137 44.6380
-88.0137 44.6380 -88.0110 44.5984
-88.0110 44.5984 -88.0254 44.5801
-88.0254 44.5801 -88.0476 44.5639
-88.0476 44.5639 -88.0461 44.5450
-88.0461 44.5450 -88.0262 44.5256
-88.0262 44.5256 -87.9960 44.5434 <>