Latest Contributions by ChuckTurlington

Hello, I have been learning Transformation concepts working with matrix algebra to develop a basic 2d conformal transformation calculator in excel.  The scale is developed as a relationship between line segment lengths between one coordinate system and another.  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.  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.  I wonder if someone can confirm my understanding above, or if a reference could be recommended that may explain the differences between the two scales. ... View more

Hello, I have ArcScene 10.4.1. I researched the Esri University courses for ArcScene, but not finding any courses related to ArcScene.  Anyone have a link or suggestions why I cannot find information on ArcScene?  There is some on YouTube but would prefer to go thru Esri for the training if possible.  Is ArcScene getting phased out, is why there is no Esri information available? ... View more

Hello, I am using ArcMap 10.4.1. My question does not pertain directly to ArcMap, but to an excel 3d similarity transformation calculator I am attempting to develop.  I am using a decent text reference (Datums and Map Projections, by JC Iliffe) that gives me 4 of the matrix (vector) relationships but, beyond setting the provisional values to zero as a first approximation, I am unclear what additional assumptions are being made to solve all the variables such as rotations about each axis, lambda, etc..  My example is not a 3d Helmert 7 parameter type, which I would actually prefer.  So I have to ask, does anyone have a 3d Helmert 7 parameter transformation example that has a little more detail beyond the first assumption to assist in solving? ... View more

Hello, I am using Arc Map 10.4.1. I am at odds with the terminology of "Geographic" coordinate and inquire for a better understanding.  I have heard many interpretations of this term.  Such as: a datum is geographic if one is using lat-long coordinates.  Which I have always assumed belong to a "round" earth.  However, there are graticules associated with a flat map, that I believe, sometimes have lat-long, such as along the edges of a quad map.  When viewing graphics set to a coordinate system like Arc Map, I understand that the geographic coordinate is actually flat, but allows 3d data to be added to the map.  But with a cad application like AutoCAD, the opposite is true, one cannot add data to a geographic coordinate, but rather, must be in a projected one such as a state plane, to add 3d data.  I find the subject somewhat confusing and look to Esri for some explanation of this "Geographic" concept.  So I have ot ask, is it possible to have geographic coordinates for a flat map, as well as a 3d datum, and is the term really just another way to refer to a lat-long coordinate format? ... View more