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2
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0answers
28 views

Is there a method to tell which hemisphere a point belongs to, in WGS84 geoid, where the equator is an arbitrary ellipsis?

I use the WGS84 geoid (because I'm working with a GPS chip). I define an ellipsis that splits the surface in two parts, lets name these 'A' and 'B'. This ellipsis is defined by two points 'a' and ...
3
votes
2answers
118 views

What programs would allow for the mapping of a geoid in 3d?

I would like to find a method for plotting an exaggerated geoid (e.g. topography): I primarily use R for my work but would be interested in other open source software options (e.g. QGIS w/ GRASS). ...
1
vote
2answers
208 views

How do you convert SRTM HGT elevations from WGS84 into meters above sea level?

I am building a JavaScript script that reads binary HGT files - as generated by the SRTM - and converts the data into bitmaps viewable in your browser. You can try out the script and view the source ...
1
vote
1answer
36 views

Is it due to irregularity of geoid, we cannot convert the height between spherical datum and local datum by cs2cs?

Is it due to irregularity of geoid, we cannot convert the height between spherical datum and local datum (which uses locally defined geoid and height) by cs2cs? What I mean is that, by using cs2cs, ...
2
votes
0answers
192 views

Which of EGM96 geoid or WGS84 ellipsoid fits the earth better?

ImageCredit Question If we separately add up |H| and |h| over the earth surface, which of the sums come out smaller? Background There is a phrase in the tag description of "ellipsoid" that says ...
3
votes
3answers
421 views

“Horizontal” and vertical datums terminology

I have heard people referring to as a horizontal datum to models such as WGS84 and as a vertical datum to geoids. The former is primarily used for determining latitude and longitude but also the ...
3
votes
0answers
151 views

Can GDAL Perform Vertical Transformations?

Can GDAL perform vertical transformations? If the answer is yes, please indicate which amongst these listed pages can explain how exactly to accomplish vertical transformations? If there is some ...
2
votes
0answers
48 views

How do you compute vertical transformations in QGIS?

How do you compute vertical transformations in QGIS? Ideally, the procedure / plugin will allow the loading of sundry geoid models.
2
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0answers
117 views

Height of the geoid in ECEF coordinates

I know that the relationship of geoid height N and ellipsoid height h to orthometric height H is defined by H = h - N, but what if I have some position in Earth-Centered-Earth-Fixed (ECEF) ...
21
votes
3answers
464 views

Are ellipsoids a mathematical necessity?

The literature usually just tells us that the Geoid is complex to describe mathematically and that we therefore fit different Ellipsoids to approximate it. Are these Ellipsoids mathematically ...
4
votes
1answer
870 views

Specification for US Census GEOID?

I'm writing a program that needs to generate GEOID values from 2000 and 2010 Census data, to link the census data to TIGER/Line records. I'm starting with the state, county, region block, etc, values ...