Appendix C.9, Page 1 of 5

DOQ FILE NAMING CONVENTIONS FOR CD-ROM MEDIA

The DOQ files must reside in a single root directory with a maximum of 12 DOQs per CD-ROM. All four quadrants of a 7-1/2 minute quadrangle (NW,NE,SW,SE) should reside on the same CD-ROM. The naming convention for DOQ files on CD-R media follows the data set naming convention used in the USGS National Digital Cartographic Data Base. Here is a brief description of the naming convention.

Sample File Name: tyyxxxzz.dds

t ‑ indicates type of quad:

O = Orthophoto (Black and White) -- note, this is the capital letter “O”

C = Color Infrared

yy ‑ indicates southeast latitude of the one‑degree block in which the quad resides

xxx‑ indicates southeast longitude of the one‑degree block in which the quad resides

zz ‑ is the 7.5‑minute section number of the one‑degree block in which the quad resides

(reading left to right from northwest corner)

.dd ‑ indicates the 3.75‑minute quarter of the 7.5‑ minute quadrangle (NE, NW, SE, SW)

s ‑ indicates file type: standard DOQ file with header attached [s]

EXAMPLES:

Location of these examples are shown as a shaded boxes in Table.

O4309101.NWS ‑ A standard DOQ file with header attached, for the northwest 3.75‑minute quarter of the first 7.5‑minute quadrangle of the one‑degree block whose southeast corner is 43‑degrees north latitude and 91‑degrees west longitude.

O4309108.NES ‑ A standard image file, for the northeast 3.75‑minute quarter of the eighth 7.5‑minute quadrangle of the one‑degree block whose southeast corner is 43‑degrees north latitude and 91‑degrees west longitude.

Appendix C.9, Page 2 of 5

44° 00¢ 00²

52 30

45 00

37 40

30 00

22 30

15 00

7 30

92° 00¢ 00²

43° 00¢ 00²

91° 00¢ 00²

The file naming convention for 7.5-minute Digital Orthoimagery is the same convention used for 3.75-minute Digital Orthoimagery (DOQ). The only difference is the 3 character extension. For 3.75-minute DOQs, the quadrant is indicated in the extension (for example C4409101.NES). For 7.5-minute DOQs, the extension is simply “.doq”. The first 8 characters of the file name are determined from the decimal latitude and longitude of the SE corner of the 7.5-minute cell for both 3.75 and 7.5-minute cells according to Table 1. Because the longitude width of the cell varies in Alaska (see Table 2), some additional rules are required to determine the file name.

Appendix C.9, Page 3 of 5

Table 1. Numbering for 7.5-minute geographic cells for Digital Orthoimagery

44° 00¢ 00²

52 30

45 00

37 30

30 00

22 30

15 00

7 30

92° 00¢ 00²

43° 00¢ 00²

91° 00¢ 00²

In Alaska, the decimal degrees of the latitude and longitude must be considered in determining the correct cell identification. For areas between latitudes 62 and 68 degrees, the longitude is a multiple of 7.5-minutes and all southeast corners fall on the 7.5-minute reference grid of Table 1. For other latitude ranges, the calculation follows the rule of finding the 7.5-minute grid that is to the right(east) in Table 3. For example, the 7.5-minute Alaska cell, Seward B-8 NW, has a southeast corner latitude of 60.3750 and a longitude -149.8125. The correct 7.5-minute cell number is 34 (see Table 3). This can also be checked in the GNIS cell_extent table with the equivalent MRC code which is D7. For the 7.5-minute Seward B-8 NW, the file name for a grayscale orthoimage would be O6014934.doq. Another example is Juneau C-3 SW which has a latitude of 58.5000 and a longitude of -134.8333. The cell number would be 26 as .8333 falls between .8750 and .7500. The .7500 value is to the right (east) so the correct cell number is 26. The file name for Juneau C-3 SW would be O5813426.doq. This scheme insures a unique value for the corner that falls in the correct one degree block of latitude and longitude.

Appendix C.9, Page 4 of 5

Table 2. 7.5-minute DOQ Divisions in Alaska

Latitude Range

7.5-minute Map Cell Longitude Width

in minutes

7.5-minute Map Cell Longitude Width

in decimal degrees

54-59

0.16667

59-62

11.25

0.18750

62-68

0.25000

68+

0.30000

Table 3. Decimal and Map Reference Code (MRC) equivalents for DOQ numeric codes

01=H8

02=H7

03=H6

04=H5

05=H4

06=H3

07=H2

08=H1

64.0000

09=G8j

10=G7

11=G6

12=G5

13=G4

14=G3

15=G2

16=G1

.8750

17=F8

18=F7

19=F6

20=F5

21=F4

22=F3

23=F1

24=F1

.7500

25=E8

26=E7

27=E6

28=E5

29=E4

30=E3

31=E2

32=E1

.6250

33=D8

34=D7

35=D6

36=D5

37=D4

38=D3

39=D2

40=D1

.5000

41=C8

42=C7

43=C6

44=C5

45=C4

46=C3

47=C2

48=C1

.3750

49=B8

50=B7

51=B6

52=B5

53=B4

54=B3

55=B2

56=B1

.2500

57=A8

58=A7

59=A6

60=A5

61=A4

62=A3

63=A2

64=A1

.1250

-146.0000

.8750

.7500

.6250

.5000

.3750

.2500

.1250

61.0000

-145.0000

An alternate method of determining the correct grid number is to use the Map Reference Code (MRC) listed for the 7.5-minute cell in the Geographic Names Information System (GNIS) listed in the Cell_Extent table. The equivalent MRC code and DOQ grid number are shown in Table 3.

Appendix C.10, Page 1 of 1

GUIDELINES FOR LABELING CDS AND/OR JEWEL CASES

o Volume ID number.

o Project block name and State(s), or AMS assignment name.

o Four-digit identification number for USGS assignment included (do not put more than one assignment on a CD.

o Type of data (DEM or DOQ) and number of data files

o Contractor’s name.

o Date of shipment.

o Delivery lot number.

o CD number in delivery lot (e.g. CD 1 of 4.).

o List of quadrangle names contained on CD.

o List of file names contained on CD (see sample).

o Include separate paperwork list of quads with diapositive and CD reference.

SANTA CATAILINA IS. CA 1 OF 2

6207

VOL 1998105B202

FILE NAME NAME QD

----------------- --------- —

03311836.NES SANTA CATALINA WEST NE

03311836.NWS SANTA CATALINA WEST NW

03311836.SES SANTA CATALINA WEST SE

03311836.SWS SANTA CATALINA WEST SW

03311837.NES SANTA CATALINA NORTH NW

03311837.SES SANTA CATALINA NORTH SE

03311837.SWS SANTA CATALINA NORTH SW

VOLUMEID 19981055B202

---End of Appendix C.10—