[mapserver-dev] Scale calculation discrepancies

[Shawn Gervais]

Devs,

I've been trying to figure out why layers, which use MIN/MAXSCALEDENOM 
have labels and layers turn on seemingly at incorrect scales. I hacked 
mapdraw.c to show me map->scaledenom in msDrawMap(), and these numbers 
are, in some cases, dramatically off from what various WMS clients 
report the scale as.

Do I have some kind of misunderstanding of what the scale denominator 
is? If not, how does one use MIN/MAXSCALE so that it behaves predictably?

Here's my data:

MS Scl		ArcMap Scl	MS Fract'n of AM
95688		127671		0.74948892074159362737035035364335
127584		170228		0.74948892074159362737035035364335
170307		226971		0.75034696062492565129465878900829
302421		403504		0.74948699393314564415718307625203
403228		538006		0.74948606521116864867678055635067
955801		1275273		0.74948736466623224987904550633472
1275868		1700364		0.75034992507486632274030736948089
1700306		2267152		0.74997441724242573942991030155896

(In this case, WMS requested EPSG:4326, data in EPSG:42102/EPSG:3005)

MS Scl		uDig Scl	MS Fract'n of UD
801614		698182		1.1481447530873038835146136680694
356612		308959		1.1542372936214837567444223990886
162279		140569		1.1481447530873038835146136680694
10212		20656		0.49438419829589465530596436870643
2423		4198		0.57717960933777989518818484992854

(In this case, WMS requested EPSG:3005, data in EPSG:42102/EPSG:3005)

-Shawn