Set and measure elevation above sea


#1

So, my model has a geolocation, which i guess also came with an altitude.
If it did so, is there a way to measure/reference (and therefore adjust) that altitude?

The Background being, i have a House plan, and need to put some heights in. Some above sea level
and some above/below my local reference. (marked with ±0.00 in the plans)

So, this could be also in LayOut, as a measuring tool that let’s me just sample points, and then adds a label, with the absolute or relative altitude.

But i guess such a Tool is Not available…


#2

I don’t think you get elevation so easily. See this topic: How can I check altitude of geolocation infomation?


#3

Thanks. Reads like there’s no way to pull the absolute height in any way, but for SU there’s a plugin to. Place a label showing the height from the model’s zero point. Will try that.
Or has anyone other suggestions?


#4

When you geo-locate a model, the reference data is written into a “GeoLocation” attribute dictionary.

See this post for a snippet of Ruby, and the link to a nifty inspector extension to view attribute dictionaries:
Finding and Exporting Google Earth Coordinates for survey

and for some examples (explaining the values of TranslationZ is in inches,) see:
Astrodynamically Correct Shadows at Altitudes Much Greater than Z=0


#5

Thanks Dan. That’s way over my head, but it reads as if a plugin coud potentially read these absolute heights, just like @TIG’s Coords-Tag from Datum does for the relative height.


#6

Yes he could update that extension (or his TIG: Add Height from Datum extension,) to add the two together, and display absolute elevations rather then relative to the origin’s Z.

This option should only be made available, if the model is geolocated and the “GeoReference” dictionary is present.

I suppose you’d formally request features in his SCF plugin thread:
http://sketchucation.com/forums/viewtopic.php?p=193238#p193238


#7

Above sea level is not a fixed value.
It is a strong function of local conditions and in fact some locations in costal regions publish their own information to be used in their locale and probably based on a number of years ( 7 comes to mind) of historical data. The Ordance Survey for England, some of the Pacific Islands, probably the Inter Coastal water way areas of the US, etc
Here is a good starting point for some reading ; https://www.e-education.psu.edu/natureofgeoinfo/c2_p16.html#comment-6996 but this mostly USGS type info;
https://en.wikipedia.org/wiki/North_American_Datum this has a link at bottom of page for the North American vertical datum of 1988
You question is so generic it is impossible to give an answer that could help since we do not know the general location you are dealing with. I doubt there is one plugin that will be valid for world wide use because of the number of different data bases out there so, it seems the first step is to find the data base you need to use.


#8

Taken literally, it varies every second but usually what is meant by the expression is the vertical distance to the datum of the currently used map coordinate system. Historically it has been determined as the median sea surface level over a time at a specific location. It used to be marked, often with a metal rod inserted in a rock.

The largest World Heritage site is the so-called Struve Geodesic Arc. It is a chain of triangulation points that stretches from northern Norway to the Black Sea.

Anssi