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**Scanned Film Products**

**INFORMATION SHEET**

**May 2008**

-   **Is it possible to purchase scanned photography from APFO?**

> Yes, APFO will create image scans for customers from the photography
> in our historical film library. APFO will also scan film flown for the
> NDOP or NAIP programs at a ground sample distance (GSD) smaller than 1
> meter. Scanned images are made from original film whenever possible
> and are provided in a standard tiff format. This imagery is not
> georeferenced, or ortho-rectified.

-   **What pixel resolutions are available?**

> The standard scan is at 25 microns, which will produce a 1016 Dots Per
> Inch (DPI; sometimes referred to as PPI - Points Per Inch) image. This
> is comparable to a 1 meter (3.2') pixel resolution for film flown at a
> 1:40,000 scale. The highest scanning resolution available, at 12.5
> microns, produces a 2136 DPI image; this will be comparable to a 0.5
> meter (1.6') pixel resolution image. A matrix on the following page
> provides an idea of what scanning resolution will produce the desired
> pixel resolution for differing scales of photography.

-   **What is a micron, and how does it relate to the pixel
    resolution?**

> A micron is a unit of measurement equal to one millionth of a meter.
> One micron equals 0.00003937 inches. It is the unit used in scanning
> to determine pixel sizes. The highest resolution available at APFO,
> 12.5 microns, will contain more pixels per inch, and more dots per
> inch (DPI). Pixel size and the number of DPI are inversely
> proportional.
>
> The formula to calculate DPI from microns is:

a)  number of microns/1,000,000

b)  that amount \* 39.37 (number of inches in a meter)

c)  the inverse of that number

> Example: 20 microns/1,000,000 = 0.00002;
>
> 0.00002 \* 39.37 = 0.00078; 1/0.00078 = 1282 DPI.
>
> The Ground Sample Distance for the scan will depend upon the scanning
> resolution and the scale of the original photography. The matrix on
> the second page will find the correct scanning resolution for a
> desired GSD.
>
> The formula for finding Ground Sample Distance is:
>
> Scale of Photography/ DPI/inches in a foot
>
> Example: 40,000/1700 = 23.529/12 = 1.96'

-   **What about scale on the digital photography?**

> Scale is irrelevant with digital imagery because the user can zoom to
> different scales in the screen display. Ground sample distance, (also
> known as pixel resolution) is the critical element with digital
> photography, because it defines how much area on the ground is
> represented by one pixel. A 1 meter pixel resolution would be 1 meter
> on all four sides, with a total area of 1 square meter. A two meter
> pixel resolution would have a pixel that is 2 meters on each size, and
> would cover an area of 4 square meters.
>
> When working with the digital scans, the user can see more detail in a
> scanned image than in an enlarged photograph.**\
> **

-   **Do I need to know what scanning resolution I want before
    ordering?**

> The Customer Service Section at APFO will assist in deciding the best
> options for your order. However, it is a good idea to become familiar
> with the information in the matrices on the next page, and to see how
> the scanning resolution, original photographic scale, and scanned file
> size relate to each other.
>
> For some high altitude photography, a higher resolution scan may not
> be able to capture any more detail than a somewhat lower resolution
> scan. The APFO staff will be able to assist with making that decision.

-   **How can I find the original photo scale**

> The scale is given in the Imagery Catalogs available on the APFO
> website. An example is given on the next page.

-   **Will the scanned negative film be negative?**

> All scans will be positives.

-   **What are the delivery options for scanned photography?**

> Delivery options will vary depending on the file size. They could be
> sent on CD, DVD, or portable hard drive. See the table on the next
> page for more details

-   **What is the cost for scanned imagery?**

> \$13.00 per scan, as of May 2008.

Table 1: In the imagery catalog, the **scales** for film are listed
under the abbreviation **SCL**. RES indicates resolution in digital
projects. In this case the FSA film is 1:40,000 and the "other" is
1:60,000.

RES BND

PROG %COV YEAR SCL FILM FMT QTY RA REMARKS

FSA 100 1990 40 BW LI 3 N

OTHER (P) 1984 60 BW LI 1 N

Table 2: A higher resolution micron scan (lower number) will contain
more Dots Per Inch (DPI) and will cover a smaller Ground Sample Distance
(GSD). The area covered will depend upon the scale of the original
photography.

  -------------- ---------------------- -------- ---------- -------- -------- -------- -------- -------- -------- --------
  **MICRONS**    **12.5**               **15**   **17.5**   **20**   **25**   **30**   **40**   **50**   **60**   **70**

  **DPI**        2136                   1700     1515       1282     1016     850      636      508      425      363

                 *Ground Sample                                                                                   
                 Distances in Feet*                                                                               

  **1:80,000**   3.1\'                  3.9\'    4.4\'      5.2\'    6.5\'    7.8\'    10.5\'   13.1\'   15.7\'   18.4\'

  **1:60,000**   2.3\'                  2.9\'    3.3\'      4.0\'    6.0\'    6.9\'    7.8\'    9.8\'    12.0\'   14.0\'

  **1:40,000**   1.6\'                  1.9\'    2.2\'      2.6\'    3.2\'    3.9\'    5.2\'    6.5\'    7.8\'    9.2\'

  **1:38,000**   1.5\'                  1.8\'    2.0\'      2.5\'    3.1\'    3.7\'    4.9\'    6.2\'    7.5\'    8.7\'

  **1:24,000**   0.9\'                  1.2\'    1.3\'      1.6\'    1.9\'    2.4\'    3.1\'    3.9\'    4.7\'    5.5\'

  **1:20,000**   0.8\'                  1.0\'    1.1\'      1.3\'    1.6\'    1.9\'    2.6\'    3.2\'    3.9\'    4.6\'

  **1:15,840**   0.6\'                  0.8\'    0.9\'      1.0\'    1.3\'    1.6\'    1.9\'    2.6\'    3.1\'    3.6\'

  **1:12,000**   0.5\'                  0.6\'    0.7\'      0.8\'    1.0\'    1.3\'    1.6\'    2.0\'    2.4\'    2.8\'

  **1:7,920**    0.3\'                  0.4\'    0.44\'     0.5\'    0.6\'    0.8\'    1.0\'    1.3\'    1.5\'    1.8\'

  **1:6,000**    0.2\'                  0.3\'    0.33\'     0.4\'    0.5\'    0.6\'    0.8\'    1.0\'    1.2\'    1.4\'

                                                                                                                  

                 Ground Distance                                                                                  
                 Formula: Scale of                                                                                
                 Photography/DPI/Feet                                                                             

                 Example: 60,000/2136 =                                                                           
                 28.08/12 = 2.3\'                                                                                 
  -------------- ---------------------- -------- ---------- -------- -------- -------- -------- -------- -------- --------

Table 3: The file sizes will vary with the scanning resolution. Larger
files will require more CDs or DVDs for delivery.

  ------------------------ ---------- ------ ------ ------ ------ ------ ------ ----- ------ ------
  **MICRONS**              12.5       15     17.5   20     25     30     40     50    60     70

  **DPI\***                2136       1700   1515   1282   1016   850    636    508   425    363

  *\* DPI formula is: 20                                                                     
  microns/1,000,000 =                                                                        
  .00002 \* 39,37 =                                                                          
  .00078; 1/.00078 =1282                                                                     
  DPI*                                                                                       

                                                                                             

  **B & W SCAN (file size  337        234    172    132    84     58.5   32.9   21    14.6   10.8
  in MB)**                                                                                   

                           **Number                                                          
                           of B & W                                                          
                           Images per                                                        
                           Media                                                             
                           Type**                                                            

  **CD (media capacity =   2          2      3      5      8      11     21     33    47     64
  700 MB)**                                                                                  

  **DVD (media capacity =  13         19     27     35     55     80     142    223   321    434
  4.7 GB)**                                                                                  

                                                                                             

  **COLOR SCAN (file size  984        684    501    382    246    171    96     62    43     32
  in MB) \*\***                                                                              

                           **Number                                                          
                           of Color                                                          
                           Images per                                                        
                           Media                                                             
                           Type**                                                            

  **CD (media capacity =   0          1      1      1      2      3      7      11    16     21
  700 MB)**                                                                                  

  **DVD (media capacity =  4          6      9      12     18     27     48     75    109    146
  4.7 GB)**                                                                                  

                                                                                             

  **\*\* The file size (in                                                                   
  megabytes) required for                                                                    
  each 9.5\' x 9.5\"                                                                         
  scanned image.**                                                                           
  ------------------------ ---------- ------ ------ ------ ------ ------ ------ ----- ------ ------

-   **Who do I contact for more information?**

1)  For sales information, contact the Customer Service Section,
    APFO-USDA-FSA at 2222 W 2300 S, Salt Lake City UT, 84119-2020; call
    801-844-2922; email <apfo.sales@slc.usda.gov> or visit
    [http://www.apfo.usda.gov](http://www.apfo.usda.gov/).

2)  For more information, contact GIS Specialists Brian Vanderbilt,
    801-844-2930, or Louise Mathews, 801-844-2934.