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The projection for my state according to my country's Mapping Agency is in a specific Lambert Conformal Conic (LCC) projection. They have given values for the following parameters:

  • False Easting
  • False Northing
  • Central Meridian
  • Standard Parallel 1
  • Standard Parallel 2
  • Scale factor
  • Latitude of origin
  • Datum/GCS

When I go to ArcCatlog, to update an existing LCC projection, I can see all the parameters except for the Scale Factor:

enter image description here

How do I enter the Scale Factor? The ArcGIS help mentions this parameter but does not mention how it to be used.

A semi-related question is: How important/required is the Scale Factor? I have seen several LCC projection without the Scale Factor. Even Snyder's Map Projections: A Working Manual does not mention it, when describing the Lambert Conformal Conic projection.

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    On the contrary, Snyder has an exhaustive discussion of scale factors in the introductory chapters (Section 4, Scale Variation and Angular Distortion) as well as systematic accounts of scale for every projection he documents, including the LCC (p. 107, equation 15-4). When you change the scale factor, you change all linear measurements in your data proportionately: surely that's extremely important! If you click on the Name combobox and re-select "Lambert_Conformal_Conic", ArcGIS will surprise you: look for the scale factor magically to appear above "Latitude_Of_Origin." – whuber Aug 7 '13 at 13:02
  • @whuber: When I said that Snyder does not talk about it, I mean when he writes about the LCC, he does not mention this as one of the parameter. As for the rest of you comment, it solved my issue. Can you post that as an answer? – Devdatta Tengshe Aug 7 '13 at 15:01
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In comments, @whuber says,

If you click on the Name combobox and re-select "Lambert_Conformal_Conic", ArcGIS will surprise you: look for the scale factor magically to appear above "Latitude_Of_Origin."

The reason for this is because, in Esri software, the Lambert conformal conic (LCC) projection is "overloaded." It supports parameters for two common variants:

  1. one standard parallel plus a scale factor
  2. two standard parallels

If you attempt to edit an existing LCC definition, the display already has a list of the parameters used by that definition. Depending on which variant it is, it will either omit the scale factor or the second standard parallel parameter. If you re-initialize the projection by switching to another projection and then back, the complete list of parameters will be shown.

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