By definition an "Index" contour is every fifth contour line. It is an "index mark" to aid in figuring out elevation changes quickly. Index marks are used throughout industry to facilite many processes. Changing the definition eliminates that process and leads to errors.
Nubmber two, if your pals cannot determine elevations without intermediate contours being labeled, they do not need to be in their field.
A proper map will have adequate spot elevations to facilitate this function. And, in really flat areas, there is no rule that says additional values cannot be placed on the intermediate contours. I do this often because I know some of my clients know nothing about contours and really struggle at the simplest of interpolations.
Just as there are specific rules and practices in proper engineering detail drawings, there are rules in cartography that are often overlooked by the unskilled and uninformed. This is becoming a major problem with the implementation of several GIS systems designed by rookies that promise impossible accuracies using their products. I tend to snicker when a salesperson "guarantees" 1 cm accuracies.
Today there are a lot of guys knocking out contours that do not understand the simple concept that index contours exist and should be represented with different line weights. (Line weight??WTF??)
I often wonder how many here (other than Mr. Farrell) know how many types of contours there are and how to properly represent them ?
If you are going to try to practice my craft, please learn how to do it properly.
You really wouldn't want me to do your architectural drawings. I would end up violating the PRIME DIRECTIVE of an architectural drater and have all of my interior dimensions add up to the total displayed exterior distance. This, obviously, is a BIG no-no in the architectural world.
