Map Legend and Scale:
By Bob Nielsen, Certified Professional Soil Scientist
In July’s newsletter, I begin describing three Key map characteristics by discussing map types. The topic for is month is the third map characteristic – map legend and scale.
Scale. ― Map scale can be simply defined as the ratio of distance on a photograph or map to its corresponding distance on the ground. Map or photographic scale is a ratio expressed as 1:24,000, 1:12,000, or 1:250,000 or as an equivalent expression, such as 1 inch equals 2,000 feet. Although map scale is a fairly straight forward concept, it does constrain the amount of information depicted on the map.
For example, map publication scale is set by the publication format and is a compromise between the information presented and the physical size of the map publication. This compromise in turn affects the amount and precision of information depicted on the map product. A good illustration of this point is the NRCS soil survey report. When soil survey maps are published at a scale of 1:24,000, the smallest area of soil a soil scientist can depict is about 10 acres. However, if the publication scale is set at 1:12,000, soil scientists can depict areas of soil as small as 2.5 acres. In areas of high-intensity agriculture, such as the Corn Belt, the greater resolution provided by the 1:12,000 soil maps is an important planning and management resource used by farmers, farm managers, and agribusiness specialists. Conversely, in the grazing lands of the West, ranchers and rangeland managers are equally well served by the lesser resolution 1:24,000 soil maps.The advent of digital maps and Geographic Information Systems (GIS) allows the user to exercise more control over map content and scale. In this context, the rural appraisers can change or tailor the maps or map products to meet their individual needs. Digital map scales can be changed by zooming in or out, and the result can be clipped and published in an appraisal report. The caveat is that current digital maps are based on their published predecessors and the information’s content has not changed. Zooming into or out of the area of interest on digital maps does not increase or decrease the accuracy or precision of the information depicted. The information presented is most reliable at the publication scale whether in hardcopy or digital format.
Map legend and metadata. ― The map legend provides a number of important details about the map. Most often, the map legend of a hardcopy map includes the map name, the year published, the scale, the projection, and a distance scale. Digital spatial data and maps also have a legend that is technically referred to as metadata (data about data). Metadata is generally in a text file that accompanies a digital map or aerial photograph. This text file contains a description of the digital data and information normally found in a map’s legend and along its margins. This information becomes important when digital maps are layered in GIS or other mapping technologies to ensure that the scale and projection of each map layer are compatible.
Summary
Maps and map products in the appraiser’s toolbox can be an important part of the appraisal process and report. However, the appraiser must decide what maps or map products will improve the appraisal process and/or the appraisal report. The best map products and mapping technologies are not always obvious and will require some research and testing. Issues to be considered in the decision process are:·There are several good reference Websites that might be of assistance in considering maps and their role in the appraisal process:
Answer: To make
this change you will have to adjust the display setting. In the DataLog: go to
Edit, Preferences, Document, Display, and change the Normal Window, scale
document to the % that works for your system. You can a try different percents
by hitting the apply button at the bottom of the Document Preferences box (shown
below).

The Illinois chapter of ASFMRA is opening up this class to all UAAR users. Please see below for details.
Uniform Agricultural Appraisal Report (175-357)We would like to know what you think of the newsletter along with any comments and ideas for future issues. Comments
AgWare, Inc.
PO Box 138
Piedmont, SD 57769
Phone: 605-787-7871
Fax: 605-787-6163
Email: agware@uaar.net
Website: www.uaar.net
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