The case of missing Monon Lake

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kirk
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The case of missing Monon Lake

Post by kirk » August 19th, 2019, 5:21 pm

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.

Where is Monon Lake.jpg
Where is Monon Lake 2.jpg

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aiwetir
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Re: The case of missing Monon Lake

Post by aiwetir » 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.
- Michael

RobFromRedland
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Re: The case of missing Monon Lake

Post by RobFromRedland » August 20th, 2019, 5:49 am

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.
Life is not a journey to the grave with the intention to arrive safely in a pretty and well-preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming: WOW-What a ride!

kirk
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Location: Oregon City

Re: The case of missing Monon Lake

Post by kirk » August 20th, 2019, 7:45 am

Now you see it:
Where is Monon Lake - zoom 3 mile scale.jpg
Now you don't:
Where is Monon Lake - zoom 2 mile scale.jpg
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.
Where is Monon Lake - zoom 300.jpg
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

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aiwetir
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Re: The case of missing Monon Lake

Post by aiwetir » 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.

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.
- Michael

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Chip Down
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Re: The case of missing Monon Lake

Post by Chip Down » August 20th, 2019, 7:09 pm

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. :?:

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adamschneider
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Re: The case of missing Monon Lake

Post by adamschneider » August 21st, 2019, 9:38 pm

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:

Image

In fact, it looks like Monon Lake is getting rendered as if its shoreline were part of the border of the Warm Springs Reservation!

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kepPNW
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Re: The case of missing Monon Lake

Post by kepPNW » August 22nd, 2019, 5:45 am

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.
Karl
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aiwetir
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Re: The case of missing Monon Lake

Post by aiwetir » 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.
- Michael

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kepPNW
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Re: The case of missing Monon Lake

Post by kepPNW » August 23rd, 2019, 1:31 pm

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.
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