topic Re: Transformation Scale in Coordinate Reference Systems Questions https://community.esri.com/t5/coordinate-reference-systems-questions/transformation-scale/m-p/768342#M168 <HTML><HEAD></HEAD><BODY><P>Hi, I would say you are pretty spot on in your understanding.</P><P></P><P><SPAN style="text-decoration: underline;">Scale in a map projection</SPAN>: relates to the length of a line mapped to the reference ellipsoid vs the length of the same line in the actual projection</P><P></P><P><SPAN style="text-decoration: underline;">Scale in a 2D conformal transformation</SPAN>: ratio of lengths of a line&nbsp;in two different 2D (in your case) orthogonal coordinate systems. Pretty much the same if you develop a 3D conformal transformation for example as seen in transformation between geodetic datums.</P></BODY></HTML> Tue, 11 Aug 2020 07:29:53 GMT Pål_Herman_Sund 2020-08-11T07:29:53Z Transformation Scale https://community.esri.com/t5/coordinate-reference-systems-questions/transformation-scale/m-p/768341#M167 <HTML><HEAD></HEAD><BODY><P>Hello,</P><P></P><P>I have been learning Transformation concepts working with&nbsp;matrix algebra to develop a basic 2d conformal transformation calculator in excel.&nbsp; The scale&nbsp;is developed as a relationship between line segment lengths between one coordinate system and another.&nbsp; But my question is concerning the concept of scale as it relates to a survey perspective that scale in a transformation is used to change between grid and ground.&nbsp; It is my understanding that the two scales are different; one derived from a line segment length ration, and the other based on the earth radius, resulting in two different scales and two different processes that use these scales.&nbsp; I wonder if someone can confirm my understanding above, or if&nbsp;a reference could be recommended that may explain the differences between the two scales.</P></BODY></HTML> Thu, 06 Aug 2020 01:21:42 GMT https://community.esri.com/t5/coordinate-reference-systems-questions/transformation-scale/m-p/768341#M167 ChuckTurlington 2020-08-06T01:21:42Z Re: Transformation Scale https://community.esri.com/t5/coordinate-reference-systems-questions/transformation-scale/m-p/768342#M168 <HTML><HEAD></HEAD><BODY><P>Hi, I would say you are pretty spot on in your understanding.</P><P></P><P><SPAN style="text-decoration: underline;">Scale in a map projection</SPAN>: relates to the length of a line mapped to the reference ellipsoid vs the length of the same line in the actual projection</P><P></P><P><SPAN style="text-decoration: underline;">Scale in a 2D conformal transformation</SPAN>: ratio of lengths of a line&nbsp;in two different 2D (in your case) orthogonal coordinate systems. Pretty much the same if you develop a 3D conformal transformation for example as seen in transformation between geodetic datums.</P></BODY></HTML> Tue, 11 Aug 2020 07:29:53 GMT https://community.esri.com/t5/coordinate-reference-systems-questions/transformation-scale/m-p/768342#M168 Pål_Herman_Sund 2020-08-11T07:29:53Z