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The case of missing Monon Lake
Posted: August 19th, 2019, 5:21 pm
by kirk
Why would Monon Lake be missing from some online maps? I noticed a few weeks ago that said lake is not appearing on some maps, such as National Forest Service, National Weather Service, my brother's navigation display in his new truck, and also the ArcGIS map here on OregonHikers.org.
Re: The case of missing Monon Lake
Posted: August 20th, 2019, 12:24 am
by aiwetir
Are they all sourcing ESRI maps?
The two you put there are both ESRI sourced. Since Google maps became expensive a lot of people have turned to ESRI and OSM. OSM has the lake, ESRI does not and I know of no way to alert ESRI of errors.
It looks like Bing is using the same source.
One thing I notice is that there are other lakes in the area that are mapped as seasonal lakes (as is Monon) and these lakes have a different visual characteristic on the aerial photos which might be indicative of their seasonal nature.
Re: The case of missing Monon Lake
Posted: August 20th, 2019, 5:49 am
by RobFromRedland
aiwetir wrote: ↑August 20th, 2019, 12:24 am
Are they all sourcing ESRI maps?
The two you put there are both ESRI sourced. Since Google maps became expensive a lot of people have turned to ESRI and OSM. OSM has the lake, ESRI does not and I know of no way to alert ESRI of errors.
It looks like Bing is using the same source.
One thing I notice is that there are other lakes in the area that are mapped as seasonal lakes (as is Monon) and these lakes have a different visual characteristic on the aerial photos which might be indicative of their seasonal nature.
I wouldn't consider Monon Lake a "seasonal" lake. It exists year round - granted it has a lot of swampy area around it, but it is a real lake all year long.
Re: The case of missing Monon Lake
Posted: August 20th, 2019, 7:45 am
by kirk
Now you see it:
Now you don't:
Here's a 300% browser zoom of the 3 mile scale that shows a stream leaving the northeast side of Monon. This is a fictional stream. When the snow is melting and water is flowing, the outlet of Monon flows from a stream at the northwest side and delivers it's water to Olallie Lake.
I'm thinking it may be a software error causing this display problem. I suppose it could be a data error.
These maps were retrieved from the ArcGIS - My Map web page.
https://www.arcgis.com/home/webmap/view ... Existing=1
Re: The case of missing Monon Lake
Posted: August 20th, 2019, 10:36 am
by aiwetir
I'm not saying these are seasonal lakes, I'm saying that's the most likely explanation based on what else I see on the map in the area. As you zoom in you can see the lake change to a brown blob which isn't really explained in the legend but again that's the most likely explanation.
I would say to take it up with ESRI, but they are so hard to get answers from that it's probably not worth it trying to change a proprietary map. OTOH, anyone can edit OSM.
Re: The case of missing Monon Lake
Posted: August 20th, 2019, 7:09 pm
by Chip Down
I guess this discussion is aimed at people more intelligent or patient or perceptive than me. I have absolutely no idea what you're talking about. It's like I just stumbled into a forum discussing 17th C. French poetry.
Re: The case of missing Monon Lake
Posted: August 21st, 2019, 9:38 pm
by adamschneider
aiwetir wrote: ↑August 20th, 2019, 10:36 am
I'm not saying these are seasonal lakes, I'm saying that's the most likely explanation based on what else I see on the map in the area. As you zoom in you can see the lake change to a brown blob which isn't really explained in the legend but again that's the most likely explanation.
"Seasonal lake" would have been my guess too, but I found some
actual seasonal lakes on the ArcGIS map, and they're filled in differently:
In fact, it looks like Monon Lake is getting rendered as if its shoreline were part of the border of the Warm Springs Reservation!
Re: The case of missing Monon Lake
Posted: August 22nd, 2019, 5:45 am
by kepPNW
adamschneider wrote: ↑August 21st, 2019, 9:38 pm
In fact, it looks like Monon Lake is getting rendered as if its shoreline were part of the border of the Warm Springs Reservation!
I think you nailed it. The lake's polygon appears to not fully cross the buffer poly created for that boundary, and the two merged.
Re: The case of missing Monon Lake
Posted: August 22nd, 2019, 10:22 pm
by aiwetir
I noticed that it was the same color as Warm Springs on other maps, but that doesn't explain the other two lakes east of there that do the same thing. They are fully contained in Warm Springs.
Re: The case of missing Monon Lake
Posted: August 23rd, 2019, 1:31 pm
by kepPNW
aiwetir wrote: ↑August 22nd, 2019, 10:22 pm
I noticed that it was the same color as Warm Springs on other maps, but that doesn't explain the other two lakes east of there that do the same thing. They are fully contained in Warm Springs.
I'm not seeing those, if they're in any of the example maps from this post, for some reason. Lots of oddball cartography going on there, though. Notice, too, that the buffer for the rez boundary is fatter north of Olallie than it is south of the lake.