Have another mountain job, there two bench marks just to the east.
Using Opus and Geoid12B I'm .17' low on both benchs,,,,,,,,,,,,,, pretty good.
Using my office point and Geoid09, I'm .03' low, or .14' different.
I'm adding .17' to the Opus ellipsoid height (holding the bench marks) and applying Geoid12B for this site B-)
MightyMoe, post: 334406, member: 700 wrote: Have another mountain job, there two bench marks just to the east.
Using Opus and Geoid12B I'm .17' low on both benchs,,,,,,,,,,,,,, pretty good.
Using my office point and Geoid09, I'm .03' low, or .14' different.
I'm adding .17' to the Opus ellipsoid height (holding the bench marks) and applying Geoid12B for this site B-)
I'd consider that really good. What elevation?
LRDay, post: 334437, member: 571 wrote: I'd consider that really good. What elevation?
It is interesting, I'm of the opinion when it comes to elevations that OPUS is basically a rough number, kinda like reading your level rod to the nearest .1' for slope staking like in the old days.
When I ran the actual numbers from the CORS stations myself, I had .3' difference in the ellipsoid height from the most southerly CORS point and the most northerly CORS point.
If you hold the south CORS you hit the bench marks really close, how OPUS adjusted everything I don't know, but clearly the ellipsoid heights are not very precise. The horizontals were very tight, my adjustment and OPUS were less than .01' lat, long. There was one point I used that OPUS didn't and one OPUS used that I didn't.
I me the OPUS elevations isn't very useful for more than a rough idea, the NAVD88 bench marks are the gold standard and since they are onsite, in agreement and stable it's a no brainer what to use. So what if they aren't 7900' above some mythical sea level number, there probably will never be anyway to really know what that is.