Adjustment of Topo Elevations by Changing HI of Total Station

Yes.

Uhmmm it depends. ZA can bite you. If not close to 90. I would edit the raw total station data and recompute. Vs just lowering by a tenth.

What am I missing? ZA determines the relationship of the height of the telescope to the height of the prism. Regardless of what the ZA might be a .10' change in rod height or instrument height results in a .10' change in the elevation of the point that was collected.

Yes changing the rod or instrument height works. Taking a points file and just dropping the elevation of all points a tenth does not always work. I may have miss read but I thought he asked if he could change the elevations by a tenth only. My bad. If changing all the elevations by a tenth only is what i was referring to. Sorry I misunderstood the question.

Was just on TS for topo. Maybe my thinking isn't valid. If you raise or lower your HI, the ZA changes if you point at the prism.

Got it.

No. You sight the prism. The zenith angle is now measured. You can move the nail you are set up on up 1 foot or down 2 feet or any other change to your HI and the zenith angle to the prism has not moved, has not changed. The instrument does not know how far below it the set up point is, therefore your measured zenith angles are not affected by how far below the instrument your nail or chiseled cross is. Put in an HI of three feet or 30 feet, the zenith angle will not change.

Or another way to visualize it. If you measured the zenith angle to a point and wanted to keep that same elevation on the point but you needed to change your HI, then the zenith angle would have to change in order to maintain the same elevation. If you put in an HI of 50' instead of 5' by mistake, the elevations on all of the points you measured would be 45' too high but all of the zenith angles you measured were correct. A change of HI is all that is needed to put the correct elevations on the point.

I don't know what software you used to process your data. With Carlson survey, if you have Field-to-Finish that inserts text labels with the elevation values, the text will not update. I have to re-do the F2F process on my points that label Finish Floors, Tops of Foundations, Spot Grades, etc. with text after shifting elevations.

There is no software involved. I'm just interested in the geometry of a hypothetical situation. Because of this I learned something new in Excel. I opened a PNEZD CSV file in Excel and subtracted 0.10' from the Z column using Paste Special. You can add, subtract, multiply, or divide. No formula necessary. Unfortunately, I don't have access to any F to F software. I'm always wondering about how to fix potential errors.

Thanks for the explanation. So what you're saying is, the TS (therefore, the ZA) and the prism rod (therefore, the rod height) aren't physically changing. We're only dealing with numbers.

Do you know how to edit posts on this new website?

No need to apologize. My way of explaining things isn't always the best. This reminds me of my first time trying to figure out a data collector. The collector doesn't know where you actually are, it just cares about what the numbers are. I had a hard time with that concept.

You were in the Marine Corps? I served 1975-1979.

I was a twinkle in my moms eye during that time. USMC 2000-2005. I went in older. I was scheduled to go in the week after graduating high school but was in a barn showing off a polo pony i had worked with in shorts and leather slip on shoes during a storm. The darn barn cat ran under the horse and one leg went through the stall and other the stirrup. I was introduced to the splits. Lol. Ripped me pretty good. So 5 years before they would let me in took me 7 and I made it. Cost me my first marriage as I was doing well in the land surveying side at the time. But Other than that I enjoyed my service time. Semper Fi.

Yes to the 1st and no I don't know how to edit posts.

I don't see why you couldn't correct your shots by lowering them 0.1'

I would prefer to edit the raw data file (dont worry it will make a note in it), and reprocess. That would create a record of what I did.

Think about it. Are the measured zenith angles dependent on what instrument height you enter at the dc? No? I thought not.

There are a number of ways to go about this. How you do it depends on what software you have access to. I would use StarNet. Amend the measure ups in the raw data and rerun to calc new coordinates. There are plenty of other softwares that can be used to edit data and recalc coordinates. You could always edit the measure ups in the raw data editor of your data collector. It can be a bit tedious to get all the necessary edits done to all the shots. Some collectors are better than others. A last resort is to simply pump up the points in CAD, or Excel.

Unfortunately, I don’t have access to any F to F software. I’m always wondering about how to fix potential errors.

Oof, that's rough.

I just can't wrap my head around the idea of an organization that willingly hamstrings its staff when it comes to efficiency and quality control.

"Unfortunately, I don’t have access to any F to F software. I’m always wondering about how to fix potential errors."

If you have Carlson or C3d - or a number of other packages - you have F2f software. That doesn't help with measure up errors. But it will help with descriptor and other mapping errors. Nevertheless, Like Rover83, my mind boggles that there are still outfits out there that are not taking advantage of these simple techniques.

Does carlson cad not have a smart text type feature for labels. I thought all the big cad platforms had that. In TBC if I label the elevation as text using the smart text feature and any point elevation changes by any means like elevation adjustment or i catch a bad rod or instrument height and fix that it will update as well.