Topographic Maps & Nautical Charts
LAND INFO has topographic map coverage of over 237
countries. Our maps are available in a variety of digital formats, scales,
resolution, and projections and are fully georeferenced and formatted
for all GIS/GPS applications.
For coverage information please access the LAND INFO Geodata Catalog or contact us for a representative to assist you in your research.
Geo-referencing
Not only can LAND INFO supply you with digital
topographic maps we can supply you with all of your geo-referencing
needs. To make our products more user-friendly we can process the map
to a projection and datum of your specification.
Geo-referenceing is established by correlating
the relationship between an image (row, column) coordinate system and
a map (x,y) coordinate system, yielding a digital topographic map opening
in GIS software in precise geographic location.
 |
 |
| 16 Control points
selected from paper map |
Collars removed during
processing. |
File Format
DRGs (Digital Raster Graphics) are typically supplied as GeoTiffs however numerous options are available:
• GeoTiff
• Tiff World .tif with .tfw
• ADRG
• CADRG
• NITF
• ER Mapper .ecw
• LizardTech MrSID .sid
• JPG2000 .jp2
• Idrisi .rst
• ERDAS Imagine .img
File Sizes
The file sizes will vary according to the specified
DPI, Color Table, physical size and density of the map.
Some examples of typical files sizes:
•
400 DPI / 8bit / 20" x 30" / 1:50,000 scale = 80Mb
•
250 DPI / 4bit / 20" x 30" / 1:24,000 scale = 15Mb
Delivery Options
LAND INFO provides several different delivery
options:
• FTP
• CD-ROM
• DVD-ROM
• External hard drive (USB 2.0/USB 3.0/FireWire 400/FireWire 800/eSata)
Quality Control
Each topographic map goes through a series of
quality control steps to ensure you are provided with the highest quality
GIS data for each project. Three steps we use to achieve the highest
quality are:
- The raw topographic map is checked against
the paper topographic map to verify an accurate digital representation.
- The processed topographic map is carefully
inspected to assure that the topographic map is properly geo-referenced.
- The four edges of the processed topographic
map are compared to adjoining topographic maps to confirm proper alignment.
Map Scales
Depending upon the printing source of the topographic
maps, there are a variety of scales available for any given area of the
earth. The following are some of the typical scales for both domestic
and international topographic maps.
US Topographic
Maps
1:24,000
1:25,000
1:63,360
1:100,000
1:250,000
1:500,000 |
International Topographic
Maps
1:10,000
1:20,000
1:25,000
1:50,000
1:100,000
1:200,000
1:250,000
1:500,000
1:1,000,000 |
Global Nautical Charts
1:10,000 - 1:10,000,000 |
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