The geomorphic reason that there is flat land next to a river is because it is the flood plane. That kind of land looks tempting, but can be deadly. Obviously, GIS analysis could add some kind of distance metric from a river to a usability score, but the analyst needs to know about the problem first.
Just a bit of "ground truthing" from a professional geoscientist.
The past 30 years have yielded tons of new hazard maps, but communities refuse to implement them in any meaningful way because of capitalism.
So it really doesnt matter how good our analysis and predictive powers are if the policies are never enforced.
If the market were allowed to operate, no one would be able to afford these houses on the coast. And in many cases that would be a good thing. Instead, the politicians have decided that beachfront property is some kind of fundamental right that we should all collectively pay for.
Everyone wants to believe that they will one day own a house on the beach. Nobody wants to believe that they will one day need the best medical care.
Everyone that buys a house or land knows these maps and checks them since the last deadly flood happened a few years ago. I cannot believe that the US decided to defund the offices that help to gather these kind of information.
For example, using GIS data combined with meteorological forecasts, a hydrological model may predict water levels of rivers or flood plains. If nobody is around to run the hydrological model on today’s data, you’re not getting your flood warning today.
(Sorry for the typo.)
Freely available Lidar and derived products (via the USGS API) for nearly the entire country makes working with elevation data a pleasure.
I enjoyed the article, but what might not be obvious to readers outside the profession is that the writer does not actually work in this field. They are a clever tech, but a layperson in geospatial terms.
https://elevation.nationalmap.gov/arcgis/services/3DEPElevat...
Preview in QGIS: https://ibb.co/B5T49YBj
Grade calculations are right in qgis docs and part of their lessons, and are also top Google hits.
https://docs.qgis.org/3.40/en/docs/training_manual/rasters/t...
Even better, you'll learn about DEMs vs topo maps.
GIS is amazing, but the first and second world wars saw a lot of advances in cartography. I'd say #1 advancement goes to the near-perfecting of portable Theodolites. It's a telescope which allows you to look at one point, then look at another, and very accurately understand the angles between them. From that, with a little walking and Pythagoras, you can figure out distances, and thereby create accurate maps with relatively minimal effort and human-error opportunities.
I say "relatively minimal effort" because technique the portable theodolite replaced was sending battalions of civil servants out into the countryside with 50ft long chains and asking them to walk the length, height and breadth of the country.
There's a lot of surveyors marks hammered into things out in the world.
However those tools do not have the polish that ESRI kit does, but at leas you’re not paying the licensing!
- former ESRI consultant
Arguably they have more polish, but less GUI. The open GIS world is more CLI, database, and library driven, which can be an advantage for many users trying to build high reliability or scaling systems.
That's a lot of the reason why Esri still wins a lot of contracts.
I’ve heard that sentiment before but never understood. Can you elaborate?
When it comes to the installation itself, be prepared for a highly involved process. ESRI typically schedules two full days with your company just for the installation and you will likely need every minute of it. The setup involves a long series of steps, many of which feel reminiscent of software deployment practices from the 90s.
But yes, using the Laplacian seems natural as a metric for what he wants to measure. Coming from a physics background though, it felt weird being explained in terms of pixels in a picture what a laplacian is...
vintagedave•7mo ago