Setting the Z Factor Parameter Correctly

re: Setting the Z Factor Parameter Correctly

MappingCenterTeam — Sat, 18 Aug 2007 00:19:53 GMT

I'd rather recommend using the z-factor to adjust for different horizontal / vertical units (like meters / feet) ONLY. Brightness and contrast are best adjusted by the lighting / insolation angle in the hillshade dialog. 'Misusing' the z-factor for tht might lead to wrongly manipulating this same z-factor in other functionality (like slope, hydro), where this would generate wrong and useless results.

Posted by Josef Strobl on June 16, 2007 at 10:00 AM PDT

I absolutely agree with Josef's point regarding the potential for misusing many of the tools that rely on a Z-Factor for just using the values in the table I included. My first recommendation was to appropriatly project the data, which entirely alleviates or at least minimizes the potential for problems.

I included the lines about the other tools because I've seen too many people run a slope analysis on data that only has a GCS and while they recognize the values as garbage, they think it's the tool's fault, and give up. So, in those cases if the data must remain in a GCS, then definitely heed Josef's warning and fully extrapolate a Z-Factor conversion that exactly fits your data's extent.

Posted by Charlie Frye on June 19, 2007 at 10:12 AM PDT

Creating hillshades: workflow guidelines

Mapping Center — Tue, 11 Sep 2007 16:00:29 GMT

A few months ago I wrote a blog entry called setting the Z Factor parameter correctly , and I used the Hillshade tool as the example. Since then several people wrote into Ask a Cartographer with questions related to using the Hillshade tool, and we've

re: Setting the Z Factor Parameter Correctly

stacemaples — Thu, 27 Sep 2007 16:14:19 GMT

I've made the "ugly hillshade" an example of the necessity of projecting data in my teaching for years. Now, I find that the Hillshade tool in 9.2 will calculate & populate the Z-Factor field with a value that provides one with a perfectly serviceable hillshade. I can't find any mention of this new feature in any forums or Service Pack docs.

At the same time, ESRI has dropped the "Assumed GCS" feature (which is great, in my opinion, since it forces one to deal with Proj's & Coord Sys's) so that I've added a section to several of my sessions on defining projections (aggravatingly enough for data downloaded from the ESRI Sources).

So I wonder...

What is the motivation for "dumbing down" tools like this, while removing other "dummy" functions?

When was this feature added (9.2, SP1, 2, 3...)?

Stace Maples

Yale University Map Collection