Instability problems with large maps
We are in the process of rolling out an Avenza training for Sonoma SAR and ran into some problems which seem related to very large maps. I made a bunch of 48"x48" maps which worked beautifully at first but when other people tried to download them they would sometimes just be blank. This happened whether you were bringing them into Avenza or hitting the map directly with a web browser. Since it seemed to be related to large maps I remade all the maps to 8.5x11 until we get this resolved. We rely so much on this service we don't want it to be unstable during a search.
Sorry I didn't get to meet Matt at the Marin MLPI training. Hopefully we'll get to do that in the fall.
Comments are currently closed for this discussion. You can start a new one.
Keyboard shortcuts
Generic
| ? | Show this help |
|---|---|
| ESC | Blurs the current field |
Comment Form
| r | Focus the comment reply box |
|---|---|
| ^ + ↩ | Submit the comment |
You can use Command ⌘ instead of Control ^ on Mac
Support Staff 1 Posted by Julie on 12 May, 2020 09:59 PM
Hi Whitney,
Could you share a link to the maps with me so that I can take a look and see if iI can duplicate the problem?
Thanks,
Julie
2 Posted by Whitney Potter on 12 May, 2020 10:06 PM
I replaced the problem maps with 8.5x11 versions for fear that we were
causing strain on the server. I'll see if I can replicate the problem
and send you the link.
Support Staff 3 Posted by Julie on 13 May, 2020 03:41 PM
Hi Whitney,
A 48x48 map can be pretty huge, especially for a mobile device. They are really intended to be opened on a computer for printing. Our suggestion would be to start using the CalTopo app for sharing maps. We've been making a lot of great improvements to the app and our goal is to have everyone be able to use that instead of dealing with switching between programs. The CalTopo app will be faster and allow much easier track management in the Command Post.
For my clarification, were you having people download the map to the phone, then import to Avenza? Or were you using a QR code to load straight from the web into Avenza?
Many thanks,
Julie
Julie closed this discussion on 13 May, 2020 03:41 PM.
Whitney Potter re-opened this discussion on 13 May, 2020 06:18 PM
4 Posted by Whitney Potter on 13 May, 2020 06:18 PM
The problem showed up initially when people were trying to download into
Avenza by scanning the QR from their screen (I didn't print 48x48"
maps!) It worked fine for me. It was slower, but I was very pleased
with the usability of having such a high resolution map on Avenza. You
can zoom in and read street names and such over a very large area. But
when I rolled it out to a few team members to test some of them had
problems. Their downloaded map was a small file, Kb instead of Mb, and
blank white and it pitched a warning popup that the map wasn't indexed.
I duplicated this problem on my phone and when I tried hitting the same
map on my laptop directly from SARTopo.com I got a blank white map as
well. In this case the maps were pdfs stored in our SARTopo account. I
could understand that an older phone would have problems with such a big
file, but the problem happened directly on SARTopo. Interestingly a
successful download took a while but the failure was much quicker.
I thought that maybe I was pushing the system with such huge maps and
things seemed to be breaking so I tried remaking the maps smaller but
for a period of maybe an hour every pdf I tried to create was blank
white. Eventually things started working again and I remade the maps at
8.5x11 and had no problems. When we got in contact yesterday afternoon
I reinstated the large maps in an attempt to replicate the problem for
you, so far with no success.
I wanted to make sure that I wasn't inadvertently creating a sort of
distributed denial of service situation by having people download huge
maps. We love SARTopo and rely on it heavily for search planning and
management and the last thing we want to do is make it unstable while we
or someone else is doing a search. So please let me know if it is
advisable to use such large maps. They work great for what we are
doing, but we don't want to turn over your server in the middle of an
incident.
I'll pass on the suggestion about the CalTopo app.
thanks for your help,
Whitney
Support Staff 5 Posted by Julie on 13 May, 2020 06:25 PM
Thanks for all the great info, Whitney! While the maps are big, they should still work eventually. I'll make sure our development team is aware of this and we'll try to replicate it. No one else has reported the problem, but then again I can't imagine people are building maps that big incredibly often unless there are a bunch of searches going on at the same time. Regardless, using the maps shouldn't cause the system to break. I do think the app will work better for your team overall.
Best,
Julie
Julie closed this discussion on 13 May, 2020 06:25 PM.
Julie re-opened this discussion on 13 May, 2020 06:53 PM
Support Staff 6 Posted by Julie on 13 May, 2020 06:53 PM
Whitney,
One thing we thought of - PDFs are typically set to expire after 7 days, unless you manually set it longer when you create the map. This would perhaps explain why it worked at first when you tried, but disappeared later. Do you think this could be the case?
Julie
7 Posted by Whitney Potter on 13 May, 2020 08:52 PM
Knowing that these maps were going to be used in an on going training
over the course of a couple of weeks I set them all to keep forever.
The problems occurred within a few hours of when I made the maps.
8 Posted by Whitney Potter on 13 May, 2020 11:03 PM
Try hitting https://sartopo.com/p/5C5F and see if you get a blank white
screen. It is suppose to be a 48x48 map.
9 Posted by Whitney Potter on 13 May, 2020 11:34 PM
Hi Julie,
https://sartopo.com/p/3E44
https://sartopo.com/p/3P70
https://sartopo.com/p/5C5F
are all coming up blank too
I am attaching one of the blank maps which I downloaded in case that
helps. I have experienced blank white maps when trying to make a pdf
using google layers, but this isn't what is going on here. These are
all derived from Open Street Map and they worked perfectly when I made them.
Thanks for your help. I hope this helps make SARTopo even better.
Whitney
10 Posted by Whitney Potter on 13 May, 2020 11:38 PM
https://sartopo.com/p/5C5F seems to work now but
https://sartopo.com/p/3E44 and https://sartopo.com/p/3P70 are still
blank. Its a moving target. I hope this makes some sense on your end :-)
Support Staff 11 Posted by Julie on 14 May, 2020 12:35 AM
I am indeed running into the same problem. Thanks again for sharing. We'll dig into it.
12 Posted by Whitney Potter on 14 May, 2020 12:45 AM
Thanks Julie. I'll leave the files there until you are done.
Support Staff 13 Posted by matt on 14 May, 2020 04:11 PM
Those maps work for me. Reproducibility is going to be tricky because PDFs are cached for a while (so that repeated loads happen frequently), but that caching period isn't a fixed length of time but instead depends on how many other maps are getting generated.
I do have a theory as to what's going on. All the maps you sent us are using the OpenStreetMap layer, which comes from OSM's server. Generating a 48x48 PDF requires loading a large number of tiles, and their server may be rate-limiting our requests. Do you have the issue when generating large PDFs with another layer like USGS or MapBuilder Topo?
In the past I haven't had good luck getting Avenza to reliably load 48x48 DPFs, but that was years ago and their app may have improved since then.
14 Posted by Whitney Potter on 14 May, 2020 06:39 PM
Thanks Matt. The problem seems intermittent, but I'm glad to know that
we aren't crashing your server when it happens. I will test it with a
different data set and see if we can reproduce it. You may be on to
something with the OSM issue. I noticed one map which came up perfectly
except that one tile was garbage. Which suggests the OSM server is under
some strain. The huge maps seem to work beautifully on Avenza its just
a matter of getting them on the phone in a way that works for our not so
tech savvy searchers.
Thanks for your help, and thanks for SARTopo, as I'm sure you know, it
truly saves lives!
Whitney Potter , Sonoma SAR 164
Support Staff 15 Posted by matt on 18 May, 2020 07:18 PM
Just wondering if you were able to reproduce with a different dataset, or if it's OSM specific?
16 Posted by Whitney Potter on 18 May, 2020 10:41 PM
I actually took a different approach to solving the problem. I used
your handy custom QR feature to make maps with QR's that point to one of
my websites and then hosted the collection there as static files. That
way they serve faster and they aren't loading your server and cluttering
up our team account needlessly. I just did a collection of all the
parks in Sonoma County at fairly large size (24-30"), mostly map builder
layers, and it performed flawlessly. The things I do to convince our
graying team members to embrace technology. . .
I think you are on the right track with OSM. I experienced frequent
outages with their servers when working on a collection of 3d printed
trail maps of all the Tahoe ski areas.
Ben Lantow closed this discussion on 13 Nov, 2020 04:18 PM.