[HOT] open geology map

john whelan jwhelan0112 at gmail.com
Sat Mar 14 17:53:17 UTC 2015


So probably the best place for it would be a separate database that could
be combined with OSM data.  There is no reason why it couldn't use OSM
format and tools such as JOSM though.

I worked in a library for a while and we had a theory that if you asked
five classifiers how to classify a book you'd get six different answers.

Cheerio John

On 14 March 2015 at 13:38, Charlotte Wolter <techlady at techlady.com> wrote:

>  Sander,
>
>         I agree with most of your points and would like to add that
> surface geology is a highly specialized field requiring a great deal of
> expertise. I'm a geology buff myself, and there is no way I would attempt
> to map that. Also, there often is strong disagreement among geology
> professionals about the nature and dating of rock units, disagreements that
> make some of our set-tos about how to code sound trivial.
>         Also, there generally is a lot of local information about
> landslides and tsunami risk, courtesy of the USGS, though sometimes it is
> ignored. In Los Angeles, tsunami-prone areas are signed along major roads,
> as are the areas subject to debris flows. The recent deadly landslide in
> Oregon was in an area known to experience landslides, but apparently the
> risk was not widely publicized.
>         Tsunami risk, perhaps, could work as an overlay, and I believe
> that data is available from the USGS.
>         But, generally, I think this whole area may be too technical for
> widespread application in OSM, even though I would enjoy seeing it.
>
> Charlotte
>
>
>
> At 05:59 AM 3/13/2015, you wrote:
>
> I think this suggestion belongs more on the general OSM talk or tagging
> list than on the HOT list, but anyway.
>
> There are already a number of ways to tag surface, like surface=*,
> natural=*, landuse=*, landcover=*, ... Just read the wiki about those (f.e.
> http://wiki.openstreetmap.org/wiki/Key:natural )
>
> There's also a convention in OSM about sub-tagging. F.e. you could tag
>
> natural=rock + rock=sandstone
>
> Thus I guess most of what you want is already possible in OSM. You should
> only try to add a few more specific conventions (f.e. about the types of
> rock).
>
> I probably don't really get your 3D attempts, but the general concensus is
> that it's hard to get in certain places, and thus you can't make a uniform
> map of heights or angles. As such, OSM contains no height or slope data
> (apart from the elevation of some peaks), but leaves this to professionals
> (such as the NASA). It isn't so hard to extract a general slope from good
> precision elevation data, so there's no point in including it directly in
> OSM data (with the right preprocessor, it can get rendered on the map
> anyway).
>
> So that doesn't belong in OSM, but it isn't the biggest problem IMO. The
> biggest problem I see in your attempt is ignoring that OSM is a
> crowdsourced effort. For crowdsourcing, you need a crowd, and that crowd is
> most easily found in populated places. Your effort seems to focus on areas
> with a low population (a city isn't very vulnerable for a landslide). But
> sadly, there's no crowd around there, so the most we would be able to do is
> some mapping from aerial pictures. This shouldn't hinder you from starting
> the project, but you shouldn't have very high expectations from it.
>
> Regards,
> Sander
>
>
>
> 2015-03-12 22:03 GMT+01:00 Hazel <hlhj2 at srcf.net>:
>  Dear All,
>
> Can we again discuss putting geological data into OSM? Specifically, I'd
> like a recommended way to tag fault lines and surface geology polygons.
>
> This e-mail assumes the reader knows nothing of geology, apologies to
> everyone else.
>
> First, the usecase: geological data saves lives in natural disasters, it
> is useful for common activities like agriculture, and it is interesting in
> its own right. It can also be usefully collected by amateurs.
>
> I am not suggesting that OSM should produce disaster risk maps, or
> recommendations for farmers. I am saying OSM could collect the data that
> would allow experts to quickly and easily make these things.
>
> Using OSM contours, they can work out areas of flood risk and tsunami
> escape routes. Using contours and and basic geological information, they
> can work out areas of landslide risk (landslides kill more people than
> volcanoes or floods or earthquakes, but they kill a few dozen at a time).
> If we map faults, they'll know more about where earthquakes are likely to
> happen (you know the photos of roads after earthquakes, offset by a few
> centimeters? The fault is the plane where the offset happens, and
> earthquakes use the same faults over and over again). If you map areas of
> shallow bedrock vs. unconsolidated sediment, you know which areas may
> suffer soil liquifaction in an earthquake.
>
>  https://en.wikipedia.org/wiki/Soil_liquefaction soil liquifaction
>
> Technical infodump:
>
> To make a geological map, you map areas with similar surface rock or
> sediment2. You describe them (anything from field IDs like "greenish rock
> #2" to detailed technical descriptions) and give them proper names (e.g.
> "the Tunbridge Wells Sand Formation").
>
> Having mapped the boundaries between different rock types, you can also
> trace faults and the line of folds in the rocks. These all obviously exist
> in 3-D, but are usually represented on 2-D maps. Just mapping the 2-D trace
> is enough for many purposes.
>
> OPTIONAL EXTRA 3-D info:
> If you want to add more information about the third dimension to a two-D
> map, there are conventions for that. You specify a line (along the axis of
> the fold, or on the steepest line down the fault plane or boundary plane).
> You map the direction of this line. Then you measure the angle between the
> line and the horizontal, and write in on the map (next to standard symbols:
> for a plane, a T-shape, and for a fold axis, an X with two or three of the
> lines turned into arrows pointing in the two or three downhill directions).
>
> Plane:
>  http://web.arc.losrios.edu/~borougt/StrikeAndDip.jpg
>
> Fold:
>  http://bc.outcrop.org/images/structural/press4e/figure-11-16b.jpg
>
> Planes on either side of a fold:
>  http://courses.missouristate.edu/EMantei/creative/GeoStruct/strkdip.jpg
>
> This is actually fairly easy to explain in 3-D, but not in 2-D, and I
> don't know of a good video. We could make one.
> END OPTIONAL EXTRA
>
>
> Example:
> Let's look at the Weald area of the UK, since it is well-mapped.
>
> Read:
>  https://en.wikipedia.org/wiki/Weald#Geology
>
> Terms:
> "Lower Cretaceous" and "Upper Jurassic" describe age (lower means older)
> "rocks", "chalk" and "sandstone" describe rock type
> "sands" and "clays" describe sediment type
> "Purbeck Beds", "Ashdown Sand Formation" and so on are proper names of
> groups of rocks/sediments. These names are hierachical, like taxons, and
> are in databases (for the Chalk Group that forms the White Cliffs of Dover:
> http://www.bgs.ac.uk/lexicon/lexicon.cfm?pub=CK).
>
> The cross-section may help make the 2-d map make sense.
>
> To see how faults and folds (synclines/synforms, that sag, and
> anticlines/antiforms, that hog) are mapped as lines, see this map:
>
> https://commons.wikimedia.org/wiki/File:Geologic_map_SE_England_%26_Channel_EN.svg
> (just gives rock ages, not type).
>
> Faults are usually much more obvious on small-scale maps than they are on
> this map.
>
> For sediments, there exist multiple soil classifications, with mappings
> between them, and OSM could support them all, but the classes we have
> (sand, gravel...) would be enough to start with.
> Examples:
>  https://en.wikipedia.org/wiki/Australian_Soil_Classification
>  https://en.wikipedia.org/wiki/USDA_soil_taxonomy
> etc.
>
> QGIS is increasingly used for geological mapping, so it works increasingly
> well with many other geological tools. QGIS is already well-integrated with
> OSM. The barrier for geologists new to OSM to upload their maps is
> therefore low. Classes of students could do it.
>  http://wiki.openstreetmap.org/wiki/QGIS
>
> End infodump, requests for clarification and corrections welcome.
>
> Could anyone suggest a set of minimal changes that would make it possible
> to enter data like this? As I said, just having a recommended way to enter
> a surface geology polygon, a geological contact line (between two
> polygons), and a fault line (with optional dip direction and inclination)
> would be very useful.
>
> Pseudo-3-D perfection would also allow keeners to input the contact
> between two rock formations (line, with dip direction and inclination) and
> input folds (line, with dip inclination), but this can also wait.
>
> Regards,
> Hazel
>
>
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>  Charlotte Wolter
> 927 18th Street Suite A
> Santa Monica, California
> 90403
> +1-310-597-4040
> techlady at techlady.com
> Skype: thetechlady
>
>
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