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Fix typos in older posts

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~lucidiot 2024-03-10 14:19:36 +01:00
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@ -1426,7 +1426,7 @@
<p>The initial goal for designing and documenting GeoRSS was to keep the encoding of geography on the Web from fracturing into various encodings the way RSS ended up, with multiple similar implementations.</p>
<footer>—<a href="https://docs.ogc.org/cs/17-002r1/17-002r1.html" target="_blank"><cite>OGC GeoRSS Encoding Standard</cite></a>, 2017-08-18</footer>
</blockquote>
<p>Considering that the three namespaces we saw in the previous post appeared before GeoRSS, and that georss.org <a href="http://web.archive.org/web/20190602115923/http://www.georss.org/w3c.html" target="_blank">mentions the W3C Geo namespace</a>, it doesn't seem like they were starting well. However, the few remaining feeds that I know of that include geospatial information do use GeoRSS only, so I guess they won in the end. The fact that only geospatial experts would be using geospatial coordinates within RSS feeds, and that most GIS software only supports GeoRSS or name all of their RSS support GeoRSS, must have helped.</p>
<p>Considering that the three namespaces we saw in the previous posts appeared before GeoRSS, and that georss.org <a href="http://web.archive.org/web/20190602115923/http://www.georss.org/w3c.html" target="_blank">mentions the W3C Geo namespace</a>, it doesn't seem like they were starting well. However, the few remaining feeds that I know of that include geospatial information do use GeoRSS only, so I guess they won in the end. The fact that only geospatial experts would be using geospatial coordinates within RSS feeds, and that most GIS software only supports GeoRSS or name all of their RSS support GeoRSS, must have helped.</p>
<p>GeoRSS defines two so-called "serializations", called <em>Simple</em> and <em>GML</em>. In this post, we will only consider GeoRSS Simple; GML requires us to delve deeper into the mess that is geospatial information, so we'll see that at some other point in time. The goal is to have most feed producers, those that are not geospatial experts, use GeoRSS Simple, which is simple enough to be understandable by them, and have geospatial experts use GML, which they probably prefer. You can convert from GeoRSS Simple to GeoRSS GML, but not necessarily the other way around.</p>
<p>Here's an example of yet another way to represent a point in an RSS feed, but using GeoRSS Simple this time:</p>
<figure>
@ -1444,7 +1444,7 @@
</pre>
<figcaption>Example of a point added to an RSS channel and item using GeoRSS Simple</figcaption>
</figure>
<p>Where the other namespaces use two distinct tags to represent both coordinates of a point, GeoRSS uses only one tag, which is defined as a list of real numbers. While using one or two tags does not matter much whether you use one form or the other when using GPS coordinates, it does start to matter when you care a lot about altitude or work with other coordinate systems. GeoRSS Simple requires WGS84 (GPS) coordinates and represents elevation separately, so it won't ever matter in this serialization, but with GML, it will!</p>
<p>Where the other namespaces use two distinct tags to represent both coordinates of a point, GeoRSS uses only one tag, which is defined as a list of real numbers. While using one or two tags does not matter much when using GPS coordinates, it does start to matter when you care a lot about altitude or work with other coordinate systems. GeoRSS Simple requires WGS84 (GPS) coordinates and represents elevation separately, so it won't ever matter in this serialization, but with GML, it will!</p>
<p>You may also note that in the first <code>point</code>, I used a space to separate both coordinates, whereas in the second one I used a comma. <a href="https://schemas.opengis.net/georss/1.0/schema-1.1/georss.xsd" target="_blank">The official <abbr title="XML Schema Definition">XSD</abbr></a> for GeoRSS Simple defines the point as holding a list of doubles (decimal numbers stored in 8 bytes) using the XSD <code>&lt;xs:list&gt;</code> element, which defines a list of items as being space-separated only. But <a href="https://docs.ogc.org/cs/17-002r1/17-002r1.html#20" target="_blank">section 7.3</a> of the OGC standard states that a comma is also acceptable, so anyone wishing to parse GeoRSS will have to take that into account.</p>
]]></description>
<georss:point>18.5166670 33.6666670</georss:point>
@ -1706,8 +1706,8 @@ because astronomers need coffee to go through the night --&gt;
<category domain="https://envs.net/~lucidiot/rsrsss/">Tip</category>
<category domain="https://envs.net/~lucidiot/rsrsss/">Geospatial/GeoRSS</category>
<description><![CDATA[
<p>In <a href="https://envs.net/~lucidiot/rsrsss/#georss-gml" target="_blank">yet another incredibly niche blog post</a>, I described GeoRSS GML. While working on this, I got quite confused by circles, eenough to decide to just remove any mention of circles in all of the previous GeoRSS posts.</p>
<p>The <a href="https://docs.ogc.org/cs/17-002r1/17-002r1.html" target="_blank">OGC standard</a>, which is the only currently active standard, and the original archived pages for <a href="https://web.archive.org/web/20200629173428/http://www.georss.org/simple.html" target="_blank">GeoRSS Simple</a> and <a href="https://web.archive.org/web/20200629173624/http://www.georss.org/gml.html" target="_blank">GeoRSS GML</a> do not define any specific element to describe a circle. If you want to represent a circle, you can do so using the &lt;georss:radius&gt; element, which will create a <a href="https://wiki.gis.com/wiki/index.php/Buffer_(GIS)" target="_blank">buffer</a> around a point.</p>
<p>In <a href="https://envs.net/~lucidiot/rsrsss/#georss-gml" target="_blank">yet another incredibly niche blog post</a>, I described GeoRSS GML. While working on this, I got quite confused by circles, enough to decide to just remove any mention of circles in all of the previous GeoRSS posts.</p>
<p>The <a href="https://docs.ogc.org/cs/17-002r1/17-002r1.html" target="_blank">OGC standard</a>, which is the only currently active standard, and the original archived pages for <a href="https://web.archive.org/web/20200629173428/http://www.georss.org/simple.html" target="_blank">GeoRSS Simple</a> and <a href="https://web.archive.org/web/20200629173624/http://www.georss.org/gml.html" target="_blank">GeoRSS GML</a> do not define any specific element to describe a circle. If you want to represent a circle, you can do so using the <code>&lt;georss:radius&gt;</code> element, which will create a <a href="https://wiki.gis.com/wiki/index.php/Buffer_(GIS)" target="_blank">buffer</a> around a point.</p>
<figure>
<pre>
&lt;!-- GeoRSS Simple --&gt;
@ -1732,7 +1732,7 @@ because astronomers need coffee to go through the night --&gt;
</pre>
<figcaption>Examples of a circle represented as a center point and a radius in GeoRSS</figcaption>
</figure>
<p>However, <a href="https://schemas.opengis.net/georss/1.0/schema-1.1/gmlgeorss.xsd" target="_blank">the <abbr title="XML Schema Definition">XSD</abbr> defining the GeoRSS GML Profile</a> and <a href="https://schemas.opengis.net/georss/1.0/schema-1.1/georss.xsd" target="_blank">the one for GeoRSS Simple</a>, both include ways to specify a circle separately. The OGC standard <a href="https://docs.ogc.org/cs/17-002r1/17-002r1.html#7" target="_blank">has links to the schemas</a> and does not state that those schemas are not non-normative, as many other specifications do. That means that in theory, it is completely legal to use them.</p>
<p>However, <a href="https://schemas.opengis.net/georss/1.0/schema-1.1/gmlgeorss.xsd" target="_blank">the <abbr title="XML Schema Definition">XSD</abbr> defining the GeoRSS GML Profile</a>, and <a href="https://schemas.opengis.net/georss/1.0/schema-1.1/georss.xsd" target="_blank">the one for GeoRSS Simple</a>, both include ways to specify a circle separately. The OGC standard <a href="https://docs.ogc.org/cs/17-002r1/17-002r1.html#7" target="_blank">has links to the schemas</a> and does not state that those schemas are not non-normative, as many other specifications do. That means that in theory, it is completely legal to use them.</p>
<h3>Reference</h3>
<dl>
@ -1743,7 +1743,7 @@ because astronomers need coffee to go through the night --&gt;
<dt><code>&lt;<dfn>gml:radius</dfn>&gt;</code></dt>
<dd>The radius of a circle. This can have an <code>uom</code> attribute to specify the unit of measurement, which is by default <code>m</code> to represent meters.</dd>
<dt><code><dfn>uom</dfn></code></dt>
<dd>A unit of measurement. <a href="https://portal.ogc.org/files/?artifact_id=20509" target="_blank">OGC GML 3.2.1 specification</a> defines its value under section 8.2.3.6. It can be either a string, without any colons, spaces, tabs, carriage returns or line breaks, or a URL. When using strings, following the <a href="https://ucum.org/" target="_blank">Unified Code for Units of Measure</a> is recommended. For example, you could use <code>m</code> for meters, <code>cm</code> for centimeters, <code>[ft_i]</code> for feet (international definition) or <code>[ft_us]</code> for U.S. feets. It is highly likely that most systems will only support meters.</dd>
<dd>A unit of measurement. The <a href="https://portal.ogc.org/files/?artifact_id=20509" target="_blank">OGC GML 3.2.1 specification</a> defines its value under section 8.2.3.6. It can be either a string, without any colons, spaces, tabs, carriage returns or line breaks, or a URL. When using strings, following the <a href="https://ucum.org/" target="_blank">Unified Code for Units of Measure</a> is recommended. For example, you could use <code>m</code> for meters, <code>cm</code> for centimeters, <code>[ft_i]</code> for feet (international definition) or <code>[ft_us]</code> for U.S. feets. It is highly likely that most systems will only support meters.</dd>
</dl>
<h3>Examples</h3>
@ -1773,7 +1773,7 @@ because astronomers need coffee to go through the night --&gt;
<h3>Notes</h3>
<p>The <a href="https://doc.arcgis.com/en/arcgis-online/reference/georss.htm" target="_blank">GeoRSS documentation on ArcGIS Online</a> mentions supports for circles on GeoRSS Simple, but excludes them from GeoRSS GML. I would therefore advise against trying to use a <code>CircleByCenterPoint</code>. It is likely that the few GeoRSS implementations out there will only support <code>&lt;georss:circle&gt;</code>, if they support circles at all.</p>
<p>The <a href="https://validator.w3.org/feed/" target="_blank">W3C Feed Validation Service</a> does not support circles in either its <a href="https://github.com/w3c/feedvalidator/blob/ff89646c3f6869058dfcf5a3cf9b6ead49bbe42d/src/feedvalidator/extension.py#L211-L239" target="_blank">GeoRSS Simple validator</a> nor its <a href="https://github.com/w3c/feedvalidator/blob/ff89646c3f6869058dfcf5a3cf9b6ead49bbe42d/src/feedvalidator/extension.py#L732-L740" target="_blank">GeoRSS GML validator</a>.
<p>The <a href="https://validator.w3.org/feed/" target="_blank">W3C Feed Validation Service</a> does not support circles in either its <a href="https://github.com/w3c/feedvalidator/blob/ff89646c3f6869058dfcf5a3cf9b6ead49bbe42d/src/feedvalidator/extension.py#L211-L239" target="_blank">GeoRSS Simple validator</a> or its <a href="https://github.com/w3c/feedvalidator/blob/ff89646c3f6869058dfcf5a3cf9b6ead49bbe42d/src/feedvalidator/extension.py#L732-L740" target="_blank">GeoRSS GML validator</a>.
<p>Circles were probably either added before <code>&lt;georss:radius&gt;</code> was introduced, or added, then partially removed when someone noticed <code>&lt;georss:radius&gt;</code> could already do the job. Another possibility is that circles and curves are far less supported by GIS software than linear geometries, so they wouldn't be that usable anyway. This raises interesting questions: what happens if you use a circle, but also add a radius around it? Do you get a larger circle? Is the radius ignored? Does it become an approximation of a circle as a polygon, as is common with GIS software that doesn't support circles? Those questions will definitely remain unanswered, as with most things about RSS, the answer of most organizations nowadays will be "who cares?". This is why we can't have nice things.</p>
]]></description>