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ChartTiff's Original Collarless / Seamless GeoLite Topographic Maps
O40105c2 (Carter Lake, CO)
ChartTiff Original Collarless / Seamless GeoLite
JPEG Format at 125 dpi.
GeoLite's are created from our Collarless / Seamless Geo's
No Setting Clipping or Setting a Transparency Layer required.
Plug compatible with your GIS System.
ChartTiff Geo's and GeoLite's occupy the exact same geographic area and
are therefore totally interchangeable.
ChartTiff GeoLite's are reduced to 125 dpi by proprietary technology
Retains the original map quality.
In standard JPEG file format.
Includes a complementing ESRI "jpgw" world file.
Includes our Expanded world file "jpr" with additional quad related info:
map scale, datum, feet / meters and quad name.
Complete coverage of the Continental US, Hawaii and Alaska
Includes all 1:24,000, 1:100,000 and 1:250,000 scale files
Full Coverage of Alaska in 1:63,360 and 1:250,000 scale files
250 DPI resolution, 256 color palette
Projection information is selected during Check Out
Select UTM, State Plane, Latitude / Longitude or
Web Mercator
Projection
The projection information applies for complete order]
If multiple projections are required please submit multiple orders
Standard GeoTiff format enhanced with
ChartTiff Extensions
Plus ESRI "tfw" and MapInfo "tab" files
Optional JPEG format -- Selectable at Check-Out
User can add
Shaded Relief
to Original Geo's and DRG's during Check Out
A Original GeoLite or DRG Quad is available as
1 Free Download
ChartTiff Original GeoLites and DRGs are sold by:
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Normal USGS Topographic Maps With Collars
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ChartTiff Original Geo's Without Collars
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A ChartTiff Original GeoLie map is created from the scanned USGS DRG topographic maps.
The quad is first projected to your requested projection, then cropped to the map extents.
The voided areas of the map are then filled with the necessary adjacent map information to make the map and Tiff file rectangular.
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All ChartTiff Original GeoLite raster images are geometrically registered at the pixel level from map to map; even from degree to degree.
All ChartTiff Original GeoLite raster images allow for easy panning from one map to another, without worrying about map overlap and transparency problems associated with other map products.
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QUAD Naming Convention
The Quad name format was developed by the USGS and is used to specify the geographic location of a quad map in latitude / longitude coordinates. For example, for quad name O34119d6, the letter "O" specifies the map scale 1:24,000. The number 34 specifies base latitude of 34 degrees, and the number 119 specifies base longitude of 119 degrees.
Each 1:24,000 map location is 7.5 minutes by 7.5 minutes; which equates to 8 x 8 = 64 quad locations in a 1 degree by 1 degree square of geographical area. The 8 rows and 8 columns of quad locations within each square degree are designated by the last 2 letters of the quad name. In this example (O34119d6), the quad is the fourth row (the letter 'd'), and sixth column (the digit '6'). Rows are designated from 'a' (south-most) to 'h' (north-most), and columns are designated from '1' (east-most) to '8' (west-most).
The 64 quad locations for the example are:
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Latitude 35 |
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Longitude
120
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| h8 |
h7 |
h6 |
h5 |
h4 |
h3 |
h2 |
h1 |
| g8 |
g7 |
g6 |
g5 |
g4 |
g3 |
g2 |
g1 |
| f8 |
f7 |
f6 |
f5 |
f4 |
f3 |
f2 |
f1 |
| e8 |
e7 |
e6 |
e5 |
e4 |
e3 |
e2 |
e1 |
| d8 |
d7 |
d6 |
d5 |
d4 |
d3 |
d2 |
d1 |
| c8 |
c7 |
c6 |
c5 |
c4 |
c3 |
c2 |
c1 |
| b8 |
b7 |
c6 |
b5 |
b4 |
b3 |
b2 |
b1 |
| a8 |
a7 |
a6 |
a5 |
a4 |
a3 |
a2 |
a1 |
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Longitude
119
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Latitude 34
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The following table lists the partial degree
values for the bottom (south) edge
of each quad location:
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decimal |
minutes/seconds |
| a |
0.000 |
00' 00" |
| b |
0.125 |
07' 30" |
| c |
0.250 |
15' 00" |
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d |
0.375 |
22' 30" |
| e |
0.500 |
30' 00" |
| f |
0.625 |
37' 30" |
| g |
0.750 |
45' 00" |
| h |
0.875 |
52' 30" |
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The following table list the partial degree
values for the right (east) edge
of each quad location:
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decimal |
minutes/seconds |
| 1 |
0.000 |
00' 00" |
| 2 |
0.125 |
07' 30" |
| 3 |
0.250 |
15' 00" |
| 4 |
0.375 |
22' 30" |
| 5 |
0.500 |
30' 00" |
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6 |
0.625 |
37' 30" |
| 7 |
0.750 |
45' 00" |
| 8 |
0.875 |
52' 30" |
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MAP SCALES
ChartTiff maps use the USGS file naming convention, in which the first letter of the file name determines the size and scale of the file:
| Letter |
Scale |
Width |
Height |
Comment |
| R |
1:20,000 |
7.5 minutes |
7.5 minutes |
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| O |
1:24,000 |
7.5 minutes |
7.5 minutes |
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| P |
1:24,000 |
7.5 minutes |
7.5 minutes |
Orthophoto |
| L |
1:25,000 |
7.5 minutes |
7.5 minutes |
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| J |
1:30,000 |
7.5 minutes |
7.5 minutes |
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| K |
1:25,000 |
15 minutes |
7.5 minutes |
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| I |
1:63,360 |
20,22.5,30,36
minutes |
15 minutes |
Alaska only |
| F |
1:100,000 |
1 degree |
0.5 degree |
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| C |
1:250,000 |
2 degrees |
1 degree |
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The remainder of the file name includes the encoded values of
latitude, longitude, and relative location of the map image.
Note: Most 7.5 x 7.5 minute USGS maps are distributed as O files (1:24,000 scale),
but some are only available as P, L, or K files.
Therefore, some ChartTiff DRG files are only available as P, L, or K files.
ChartTiff Original Geo files (collarless/seamless maps)
are automatically processed into corresponding O files.
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