DOQ/DRG Tools

ArcView DOQ/DRG Tools Extension

Purpose of this Extension

Although ARCVIEW 3.x can read JPEG images, it cannot read USGS standard distribution DOQ’s in JPEG format from county based CD-ROMs. This is because the DOQ’s don’t have a standard .JPG extension and the georeferencing information is not in the world file format that is supported by ArcView. This extension gets around these limitations so that you can view the DOQ’s directly from CD-ROM in JPEG format without having to uncompress them.

The DRGs for Minnesota Users have been post-processed by the Department of Natural Resources to remove the collar information (the information not on the quadrangle itself including scale bar, legend, etc.) and to bring them into conformance with the DNR’s GIS data specifications (UTM Extended Zone 15, NAD83 Datum) and storage structure. There are tools in this extension that allow the user to take advantage of this structure for efficient DRG access.

This extension also allows the user to generate clipped and merged DOQs and DRGs based on the outline of a polygon shapefile. This is extremely useful if you want to digitize or use the DOQ's or DRG's extensively. These clipping routines use the EPPL7 Version 3.0c Raster based GIS available from the Minnesota Land Management Information Center

What is a DOQ?

A DOQ is a digital image of the earth’s surface that has been digitally scanned and processed to remove the distortion inherent in aerial photography. Using a digital elevation model and advanced image processing techniques, radial and topographic distortion is removed from the image providing a true planimetric product.

A DOQ image typically covers one-quarter of a 1:24,000 scale USGS topographic map plus a little overlap. The resolution of the image is quite high at one square meter per pixel. As a result of this fine cell size, these images consume large quantities of disk space. To conserve disk space the images are stored in JPEG image format which compresses the data very efficiently. In JPEG format the images average 4.5 MB but when uncompressed they average 45 mb!

What is a DRG?

A digital raster graphic (DRG) is a scanned color image of a U.S. Geological Survey (USGS) standard series topographic map, including all map collar information. The image inside the map neatline is georeferenced to the surface of the earth and fit to the Universal Transverse Mercator projection. The horizontal positional accuracy and datum of the DRG matches the accuracy and datum of the source map. The source maps are scanned at a minimum resolution of 250 dots per inch.

DRGs are created by scanning published paper maps on high-resolution scanners. The raster image is georeferenced and fit to the UTM projection. Colors are standardized to remove scanner limitations and artifacts. The average data set size is about 6 megabytes in Tagged Image File Format (TIFF) with PackBits compression.

DRGs are stored as rectified TIFF files in geoTIFF format. GeoTIFF is a relatively new TIFF image storage format that incorporates georeferencing information in the header. This allows software, such as ArcView, ARC/INFO, or EPPL7 to reference the image without an additional header or world file.

The road numbers are read from the ROAD_NUM field and placed in the center of the symbol. These road numbers can contain alpha-numerics but should be 3 characters or less in length. Longer values will result in unexpected results

Functionality Highlights

At this time this extension contains the following functionality:

Known Problems

• The biggest trouble you will likely run into with this extension is the type of TIFF file you are using. EPPL7 can handle a number of TIFF file formats including LZW. If the process fails during EPPL7 processing then it's most likely because of the TIFF format. EPPL7 will output PackBits format GEOTIFF files that can be read with ArcView 3.0 and Arc/Info. The EPPL7 3.0d update is coming and has Group 4 compression capabilities.
• Only eight registration tics can be used during the Image Rectification process.
• When Importing EPIC data files EPPL7 has a limitation of being able to export raster files that have less than 16,000 columns. This has been fixed with EPPL7 Version 3.0c.

Download Program

DOQV13.ZIP - Full Extension with Documentation (1mb)

DOQ/DRG Tools Documentation (Adobe .PDF - 1.3mb)

DOQ/DRG Tools Documentation (PowerPoint .PPT - 721k)

CLIPPERS.ZIP - DOQ and DRG Clipping Executable Programs (84k)
Remember that you need EPPL7 Version 3.0c to use these programs! (Thanks Craig!)

For more information about DOQ's follow these links:
About the DOQ Program (USGS)
What are DOQ's? (USGS)
DOQ's in Minnesota (LMIC)
DOQ's on County CD-ROMS (LMIC)

For more information about DRG's follow these links:
About the DRG Program (USGS)
DRG Detailed Metadata (USGS)
DRG's in Minnesota (LMIC)

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