checkpoint post, add images

content/sundries/a-very-digital-artifact/index.md

@@ -100,10 +100,10 @@ But at that moment, I had nothing at all. Time to get some data and see if I can
 
 # Public data
 
-My first impulse was to search [USGS](https://usgs.gov)'s website for
+My first impulse was to search [USGS](https://usgs.gov)'s website for [digital elevation
-[heightmap](https://en.wikipedia.org/wiki/Heightmap) data, but I wound up not finding anything
+map](https://en.wikipedia.org/wiki/Digital_elevation_model) data, but I wound up not finding
-appropriate. Searching now with the wisdom of experience and hindsight, I found this, which would
+anything appropriate. Searching now with the wisdom of experience and hindsight, I found this, which
-have been perfect:
+would have been perfect:
 
 [https://apps.nationalmap.gov/downloader/](https://apps.nationalmap.gov/downloader/)
 
@@ -113,8 +113,8 @@ many, many missteps.
 
 ## From space?
 
-Anyway, having not found anything I could really use from the USGS, I found [this
+Anyway, having not found anything I could really use from the USGS through all fault of my own, I
-site](https://portal.opentopography.org/raster?opentopoID=OTSRTM.082015.4326.1), from
+found [this site](https://portal.opentopography.org/raster?opentopoID=OTSRTM.082015.4326.1), from
 OpenTopography, an organization run by the UCSD Supercomputer Center, under a grant from the
 National Science Foundation. So, still hooray for public data!
 
@@ -431,7 +431,7 @@ as tall as another thing, that will still be true after being scaled), so in a s
 "accurate" (*note: more foreshadowing*).
 
 Once I had the PNG file, I used the [ImageMagick](https://imagemagick.org/script/convert.php) `convert`
-command to scale the file down to a reasonable size. Finally, I had something I could use to make a
+command to resize the file down to a reasonable size. Finally, I had something I could use to make a
 mesh:
 
 ![the heightmap made by doing a linear scale of height to brightness][scaled_heightmap]
@@ -440,16 +440,45 @@ Pretty cool, right? I thought so! The detail is pretty great; that bright spot n
 [Mt. Shasta](https://en.wikipedia.org/wiki/Mount_Shasta), for example;
 [Mt. Whitney](https://en.wikipedia.org/wiki/Mount_Whitney) is slightly taller, but not by much, and
 is part of a range so it doesn't stand out the way Shasta does. It was time to start making some 3D
-geometry with the heightmap!
+geometry with the heightmap[^time-to-mesh]!
 
 # A mesh is born
 
+My next step was to figure out how exactly to turn that heightmap into a mesh. Some searching
+assured me that [Blender](https://www.blender.org/), a free and open source 3D modeling package that
+I'd dabbled with before, would work well. For example, here's a pretty high-level walk-through of
+[how to use a heightmap to displace a mesh
+plane](https://alanedwardes.com/blog/posts/create-meshes-from-height-maps-using-blender/), which is
+definitely the first step I needed to take. Before too long, I had something that looked like this:
 
+![a very pointy california topo][pointy-california]
+
+At first glance, it looks OK, but there's so. much. detail. And it's very, very pointy; it just
+looks jagged. Check out this close-up detail of Mt. Shasta:
+
+![a very pointy mt shasta][pointy-shasta]
+
+You can tell that would not be pleasant to touch, and being able to run your fingers along the shape
+was a huge part of the appeal of the artifact.
+
+## Back to the realm of images
+
+Given that it seemed like there were a couple semi-related problems with there being too much
+detail, my first thought was to blur the heightmap, and then reduce the size of it. I used the
+ImageMagick `convert` command [to blur the image](https://legacy.imagemagick.org/Usage/blur/) a
+couple rounds, and then resized it down:
+
+![first attempt at blurring the heightmap][blurry-linear-hm]
+
+This was a little better, but still not great. A few more rounds of blurring and shrinking got me
+this:
+
+![second round of blurring the heightmap][blurry-linear-hm-smaller]
+
+With that version, I was able to produce some reasonably smooth-looking geometry in Blender:
 
 # Test prints
 
-## Back to the realm of the image
-
 # Final cut
 
 # Thank yous, lessons learned, and open questions
@@ -481,6 +510,14 @@ given how much I had to blur and decimate)?
 
 [scaled_heightmap]: scaled_heightmap.png "the heightmap made by doing a linear mapping of height to brightness"
 
+[pointy-california]: pointy_california_blending.png "the displaced mesh plane made from the first heightmap"
+
+[pointy-shasta]: pointy_shasta_close-up.png "a very pointy mt shasta"
+
+[blurry-linear-hm]: blurred_scaled_hm_3.png "first attempt at blurred heightmap"
+
+[blurry-linear-hm-smaller]: lo-rez_blurred_hm3.png "second round of blurring the heightmap"
+
 [^introspection]: The conclusion upon examination was, "I just wasn't thinking".
 
 [^math-computers]: I'm pretty sure this is more "represent shapes with math" than with a computer, but
@@ -507,3 +544,9 @@ so there you go.
 the end product was the point, but I assured him that every step I took was trying to get to the end
 product as quickly and straightforwardly as possible. Still, I did in fact wind up learning a whole
 shitload of stuff, which is nice, I GUESS.
+
+[^time-to-mesh]: Based on the timestamps of the files in the directory where I was working on this
+project, it took about ten days from the time I first downloaded a geotiff dataset to having the
+heightmap shown above, so you can imagine all the dead-ends I went down and did not share in this
+write-up.
+