The Digital Raster Graphic (DRG) is a raster image of a scanned USGS topographic map including the collar information, georeferenced to the UTM grid. This version of the Digital Raster Graphic (DRG) has been clipped to remove the collar (white border of the map) and has been reprojected to geographic coordinates.
A DRG is useful as a source or background layer in a GIS, as a means to perform quality assurance on other digital products, and as a source for the collection and revision of DLG data. DRG's can also be merged with other digital data, e.g. DEM's or DOQ's, to produce a hybrid digital file. The clipped version of the DRG is useful when working with areas that are within two adjacent quadrangles.
publication date
Acknowledgment of the USGS would be appreciated in products derived from these data.
384 Woods Hole Road
DRGs were produced through an Innovative Partnership agreement between The Land Information Technology Company, Ltd., of Aurora, CO and the USGS.
The DRG is an 8-bit color image that employs a color palette to ensure uniform colors throughout a particular DRG series. All DRG's within a series must have the same RGB value.
No additional checks for topological consistency were performed on the data.
The DRG is a faithfully reproduced digital image of the original source map. Some differences may be detected between the source graphic used and the DRG due to the RGB values assigned that particular color. The intent is to recreate those colors as near as possible. Data completeness for DRG files reflect content of the source graphic. Features may have been eliminated or generalized on the source graphic due to scale and legibility constraints. For information on collection and inclusion criteria, see U.S. Geological Survey, 1994, Standards for 1:24,000-Scale Digital Line Graphs and Quadrangle Maps: National Mapping Program Technical Instructions and U.S. Geological Survey, 1994, Standards for Digital Line Graphs: National Mapping Program Technical Instructions. Additional useable data exists in this area and can be found in the list of clipped DRGs for Puerto Rico Quadrangles (7.5 series 1:20,000) below: QUADRANGLE (PUBLICATION DATE) - FILE NAME ADJUNTAS (1960) - ADDRG83.TIF AGUADILLA (1960) - AGDRG83.TIF AGUAS_BUENAS (1982) - ABDRG83.TIF ARECIBO (1982) - ARDRG83.TIF BARCELONETA (1982) - BTDRG83.TIF BARRANQUITAS (1982) - BRDRG83.TIF BAYAMON (1982) - BMDRG83.TIF BAYANEY (1982) - BYDRG83.TIF CABO_ROJO (1966) - CBDRG83.TIF CAGUAS (1982) - CGDRG83.TIF CAMUY (1982) - CMDRG83.TIF CAROLINA (1982) - CRDRG83.TIF CAYEY (1982) - CYDRG83.TIF CAYO_ICACOS (1958) - CCDRG83.TIF CENTRAL_AGUIRRE (1982) - CADRG83.TIF CENTRAL_LA_PLATA (1964) - CPDRG83.TIF CIALES (1982) - CLDRG83.TIF COAMO (1972) - CSDRG83.TIF COMERIO (1982) - CODRG83.TIF COROZAL (1972) - CZDRG83.TIF CULEBRA (1948) - CUDRG83.TIF EL_YUNQUE (1982) - EYDRG83.TIF FAJARDO (1982) - FADRG83.TIF FLORIDA (1957) - FLDRG83.TIF GUANICA (1966) - GADRG83.TIF GUAYAMA (1982) - GMDRG83.TIF GURABO (1982) - GRDRG83.TIF HUMACAO (1982) - HUDRG83.TIF ISABELA (1960) - ISDRG83.TIF JAYUYA (1982) - JADRG83.TIF JUNCOS (1982) - JUDRG83.TIF MANATI (1982) - MNDRG83.TIF MARICAO (1960) - MRDRG83.TIF MAYAGUEZ (1964) - MADRG83.TIF MOCA (1964) - MCDRG83.TIF MONA (1944) - MODRG83.TIF MONTE_GUILARTE (1960) - MGDRG83.TIF NAGUABO (1982) - NGDRG83.TIF NARANJITO (1982) - NJDRG83.TIF OROCOVIS (1982) - ORDRG83.TIF PARGUERA (1966) - PEDRG83.TIF PATILLAS (1982) - PADRG83.TIF PENUELAS (1982) - PSDRG83.TIF PLAYA_DE_PONCE (1982) - PLDRG83.TIF PONCE (1982) - PODRG83.TIF PUERTO_REAL(1966) - PRDRG83.TIF PUNTA_CUCHARA (1982) - PCDRG83.TIF PUNTA_GUAYANES (1982) - PGDRG83.TIF PUNTA_PUERCA (1982) - PPDRG83.TIF PUNTA_TUNA -(1960) PTDRG83.TIF PUNTA_VERRACO (1982) - PVDRG83.TIF QUEBRADILLAS (1972) - QUDRG83.TIF RINCON (1966) - RIDRG83.TIF RIO_DESCALABRADO (1982) - RDDRG83.TIF RIO_GRANDE (1982) - RGDRG83.TIF ROSARIO (1964) - RODRG83.TIF SABANA_GRANDE (1966) - SGDRG83.TIF SALINAS (1982) - SLDRG83.TIF SANTA_ISABEL (1982) - SIDRG83.TIF SAN_GERMAN (1966) - SNDRG83.TIF SAN_JUAN (1982) - SJDRG83.TIF SAN_SEBASTIAN (1958) - SSDRG83.TIF UTUADO (1982) - UTDRG83.TIF VEGA_ALTA (1982) - VADRG83.TIF VIEQUES (1982) - VEDRG83.TIF YABUCOA (1982) - YADRG83.TIF YAUCO (1982) - YODRG83.TIF
While the datum of the published map is retained, this image was originally cast on the state plane coordinate system, then reprojected to geographic coordinates and may therefore be INCONSISTENT with the credit note on the image collar.
The source map is scanned to produce the DRG.
The DRG was projected and clipped to generate this version in the state plane coordinate system, NAD83 without the DRG white border
The production procedures, instrumentation, hardware, and software used in the collection of standard DRG products vary depending on systems used at the contract, cooperator or USGS production sites. The majority of DRG data sets are acquired through government contract. The process step describes, in general, the process used in the production of standard DRG data sets. 1. Production of a DRG begins with the scanning of a paper 7.5-minute topographic map (map1) on a high-resolution scanner. Scanning resolutions range from 500 - 1000 dpi with the output file running between 160-300 mb. 2. Removal of screens (descreening) and color quantization to reduce the number of colors also takes place during the scanning phase. 3. The raw scan file is then transformed and georeferenced using UTM coordinates of the sixteen 2.5-minute grid ticks, which are obtained using the in-house produced program COORDAT and stored in a ground control file. Those sixteen 2.5-minute ticks are interactively visited and assigned their respective UTM coordinates. USGS program XSHAPES4 then performs a piecewise linear rubber sheet transformation. 4. An output resolution of 2.4 meters (8.2 feet) is chosen in order to resample the file to 250 dpi. 5. The image file is converted to a TIFF and further reduced by converting the file to a run length encoding Packbits compression(type 32773). 6. The color palette of the compressed DRG is then standardized by replacing the original RGB values assigned during the scanning process with standard RGB value combinations using the in-house produced TIFFREMAP program. 7. Prior to archiving the DRG undergoes the following quality assurance procedures: a. The color index values of each DRG are checked to ensure the RGB combinations are consistent with the standardized color palette. b. All DRG files are inspected to ensure that they are geometrically consistent with normal map presentation. c. Selected DRG's are checked to ensure that data elements in the DRG metadata file correspond to the map collar information and to the information in the associated image file. d. Selected DRG's are checked for georeferencing accuracy by comparing the book value of latitude and longitude tick marks with corresponding tick intersections in the DRG image. e. Transformations are checked on selected DRG's by comparing the positions of well defined points, such as UTM grid intersections in the graphic product, with the corresponding image points in the DRG. f. The original DRG was then projected from UTM to the state plane coordinate system (Lambert Conformal Conic projection)NAD27 and then reprojected to the NAD83 DATUM. The white border was clipped using the ESRI Arc/Info software, the projection and clip processes were done by the USGS Caribbean District.
Data were projected from NAD83 state plane coordinate system to NAD83 geographic. Tool: ArcGIS > ArcToolbox > Toolboxes > Data Management Tools > Project
384 Woods Hole Road
Internal feature number.
ESRI
Color index value (0-12) referencing a color palette of RGB values from 0 through 255.
U.S. Geological Survey
Pixel value for red color palette
U.S. Geological Survey
Pixel value for green color palette
U.S. Geological Survey
Pixel value for blue color palette
U.S. Geological Survey
Transparency setting
U.S. Geological Survey
Total count of value in image
U.S. Geological Survey
Each raster entity or pixel contains a color index from 0 through 12 referencing a color palette of RGB values from 0 through 255 in which the standard colors used in the DRG are defined. (In ArcView set Color 255 to transparent to eliminate the black thin border.) USGS DRG Color Palette Digital Number Color Red Green Blue 0 Black 0 0 0 1 white 255 255 255 2 Blue 0 151 164 3 Red 203 0 23 4 Brown 131 66 37 5 Green 201 234 157 6 Purple 137 51 128 7 Yellow 255 234 0 8 Light Blue 167 226 226 9 Light Red 255 184 184 10 Light Purple 218 179 214 11 Light Grey 209 209 209 12 Light Brown 207 164 142
Draft Standards for Digital Raster Graphic.
384 Woods Hole Road
Although these data have been used by the U.S. Geological Survey (USGS), U.S. Department of the Interior (DOI), no warranty expressed or implied is made by the U.S. Geological Survey as to the accuracy of the data. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the USGS in the use of these data or related materials. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
GeoTIFF
GeoTIFF format digital raster graphic, GeoTIFF world file and associated metadata
1400 Independence Rd, MS231