Category: Ecology

Conferences, EcoHackNYC, Ecology

EcoHackNYC– Cool projects, fun new ideas, human waste, CartoDB and other flotsam.

I took a bus to New York City this weekend to enjoy the company of fellow hackers at EcoHackNYC, organized by Javier Torre and Andrew Hill of Vizzuality and Robin Kraft of REDD Metrics.  Due to delays in Pittsburg, I missed the ignite talks on Friday, arriving on NYU’s campus on Saturday morning. Several groups formed around topics and we started hacking. I worked on … Continue reading EcoHackNYC– Cool projects, fun new ideas, human waste, CartoDB and other flotsam.

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Analysis, Database, Ecology, PostGIS, Security, SQL

Postgis for breakfast: ST_Donut — Revision

A commenter on my last ST_Donut post pointed out that we were essentially using not one but two buffers and and ST_Intersection to test where a point lay.  Bad Spatial SQL. Very bad Spatial SQL. Actually, at Paul Ramsey’s PostGIS for Power Users presentation at FOSS4G this year, I think he mentioned not doing that very thing, and I chuckled to myself, “Well, even I … Continue reading Postgis for breakfast: ST_Donut — Revision

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Analysis, Database, Ecology, PostGIS, Security, SQL

Postgis for breakfast: ST_Donut

This post typed into my iPod as an homage. Assisted today by my collegue, J. Stein. Moderate obfuscation of locations is an important technique for the protection of data, say something sensitive like the nesting locations of the very rare and strange fuzzy-bellied gnat catcher. We still want to display the data, but want to make it slightly wrong. A naive approach would place it … Continue reading Postgis for breakfast: ST_Donut

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Ecology, Image Processing, ImageMagick, Landscape Position

Landscape Position Continued– Median and ImageMagick

Highlighting ridges with 250ft buffer (on 2.5ft DEM) with just ImageMagick: convert lscape_posit.png -median 100 median100.png composite -compose difference lscape_posit.png median100.png difference_median100.png Input: Output: BTW, median calculations of this size are slow, even in ImageMagick. Continue reading Landscape Position Continued– Median and ImageMagick

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Ecology, Image Processing, ImageMagick, Landscape Position, POV-Ray

Landscape Position Continued– absolutely relative position calculation

I apologize in advance– this first post will be heavy on code, short on explanation. Landscape position, e.g. previous posts, can be trivial to calculate, but to make the calculations scalable to a large area, some batching is necessary. In this case, instead of a McNab index, we’re calculating the traditional GIS landscape position. Enter my favorite non-geographic tool, PovRay… . To the difference between, … Continue reading Landscape Position Continued– absolutely relative position calculation

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Landscape Position

Landscape Position and McNab Indices (cont.2)

In one and two previous posts, I talked about McNab indices and what they mean and how to compute them.  This is a short post just showing another screenshot of a McNab mesoscale.  The previous image was from a stream valley running through the glaciated Allegheny Plateau.  This image is a stream cut through the soft shale of the Lake Plain of the Eastern Basin … Continue reading Landscape Position and McNab Indices (cont.2)

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Ecology, Landscape Position, POV-Ray

Landscape Position and McNab Indices (cont.)

I typed that last one too quickly– too many typos, but my wife says I’m not supposed to revise blogs, but move on… . So, for clarity, let’s talk a little more about McNab indices.  Field-derived McNab indices are a measure of average angle from the observer to the horizon (mesoscale landform index), or from the observer to another field person a set distance away, … Continue reading Landscape Position and McNab Indices (cont.)

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Landscape Position

Landscape Position and McNab Indices

Just a quick teaser post for our forestry/ecology readers out there.  I have a methodology developed for calculating McNab indices that directly corresponds with the field technique (unlike, as far as I know, any previous GIS-based techniques– which are probably adequate proxies). What is a McNab index?  Well there are two kinds, the minor landforms and mesoscale landforms that are field-measured topographic position or terrain … Continue reading Landscape Position and McNab Indices

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Ecology, Landscape Position, Optics

Topographic Position Index and Ecological Land Type (warning completely unrefined not quite Geologic dribble– with bad maps :) …)

Warning.  What follows is somewhat informed, but I’m no geologist.  I just play one on wordpress. Understanding the basic underlying geology and associated topography plus site history helps us achieve a basic understanding of a sites ecological potential.  At the most basic level, we expect different wildlife and vegetation dynamics in a floodplain vs. a mountain ridge.  Classification of digital elevation models can be done … Continue reading Topographic Position Index and Ecological Land Type (warning completely unrefined not quite Geologic dribble– with bad maps 🙂 …)

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