I've added a slope analysis layer that allows you to shade slopes by angle and aspect. It's a good high-level visualization of potential avalanche starting zones that can assist with safe route planning, but it's important to remember that it's also just a tool, it should be one of many in your toolkit, and is in no way a substitute for good decision making based on conditions you observe on the ground. Some known limitations are listed here: http://caltopo.blogspot.com/2012/02/ava ... lysis.html

As an example, here's Shasta shaded by slope angle:
http://caltopo.com/map.html#ll=41.4,-122.2&z=14&b=t&n=0.25&o=r&a=slp_s-11111111


And here's Shasta with the S-E aspects shaded orange:
http://caltopo.com/map.html#ll=41.4,-122.2&z=14&b=t&n=0.25&o=r&a=slp_a-11333111


You can click the + in the top right corner to switch between shading by aspect and angle, and also to enter danger-rose-style colors when shading by aspect. I'm still trying to sort out some server performance issues, so the shading may take a while to load.

This is all highly experimental, and I welcome any feedback. In particular, I had to take guesses at what slope cutoffs to use and how to actually do the shading. This info is on the bottom right of the screen, but since it's subtle:

Shading by aspect: slopes between 28 and 59 degrees are shaded, with 35-45 having dots on top to differentiate them.

Shading by angle:
20-27: green
28-34: yellow
35-45: red
46+: blue

Nice - your USGS maps are a lot more recent than TerraServer's. I also like the ability to do semitransparent overlays and to measure distances.

One feature you should steal from Acme Mapper: the ability to specify a Google "pin" marking an exact location (or better, a set of these). You can then share a URL that regenerates the map (the software just adds a list of markers like "&marker0=42.64438%2C-73.19435" to the URL that specifies the map center and the visible layer(s).)

So if you're on summitpost forum and somebody asks, "how do I find the Brutus Bushwhack up Owl's Head?" you can reply: "start leave the trail when it crosses the stream (point A on *this map*), aim to hit a logging road at about point B, follow it to point C..." without actually uploading a new map.

Have you tried logging in and creating a map? I had something that allowed you to drop markers and update the URL, but email programs tended to munge the URL so everyone was using bit.ly or similar shortening services. I decided to scrap it and store all the marker coordinates on the server side, which allows you to get a lot more detailed, add tracks, etc. with the downside of a little more overhead.

I'm not set in my ways, but before making any changes I'd like to get a better idea what's turning people off with the current approach. Is it logging in / creating a new named map? The fact that you have to switch over and effectively have 2 modes (editable map v. view w/ URL updates)? Is the functionality just too obscure?

Primarily I'm allergic to logging in on an unfamiliar website, especially when I know I have a login-free alternative. I haven't played with your build-a-map/share-a-map tools so maybe it's easier than I imagine.

I actually didn't see the build-a-map link at first, I had a hard enough time finding the view-a-map link. (Where "hard" is extremely relative, but still, a big fat image to click on would be a good addition to the front page. )

On a more general level, the interface sounds unnecessarily modal. Let users see the tools even when they're not logged in, ask them to log in when that's actually necessary - if they want to save their work, for example. (Or if you autosave, ask them to log in when they try to select a tool that would require saving.) Again, I haven't seen the build-a-map tools, maybe they take up too much screen space and/or would intimidate novice map viewers.

PS why does it bother you if people use Bit.ly? Maybe integrate with them right on your website...

OK, the map creation tool is easy and uncluttered, and sharing is effortless. I like your privacy features too (I'd change the defaults, but I'm probably more paranoid than most of your users).

The Set Defaults dialog (and/or disc icon) was a tiny bit confusing.

I still think a less modal approach would be even better, but that was quite painless once I logged in. (I happen to already have a suitable account. I fully understand why using that kind of service is attractive to a low-manpower website.) Good job.

nartreb wrote:I still think a less modal approach would be even better

Thanks for the feedback in the above two posts. On this point in particular I agree with you 100%, and if I were designing things from scratch they wouldn't have the split modes that the current version does. Unfortunately it's evolved over time from something very different, and allowing users to start making a map and then save it is complicated - there's a bunch of code that assumes a named map already exists in the DB before any markers get created on the client side. So the question becomes how much time to devote to this v. other features or additional map layers.

I don't mind people using URL shorteners at all, but I don't want the URL getting so complicated that a shortener is necessary in order to preserve it in mail programs (Yahoo seems especially bad at wrecking long URLs). I could generate my own shortcode whenever someone clicks "save this map", but there are times where it's nice when the map center and layers are directly editable in the URL, at least for techies like me.

Yeah well techies probably don't need the "share" button to know how to send the URL to their friends You could incorporate a shortening service into the example code on the how-to-share page; even use a checkbox to let users choose original or shortened URLs. (Then watch to see what people actually do.)

Note that shorteners are just redirectors - you click it and then you see the unshortened URL in your browser. (It's an antifeature that you can't find out the true destination *before* clicking, but if I had a nickel for every gripe I have about the way people use the Internet...) So anybody who wants to edit the URL still can. They don't even have to wait for that original page to finish loading.

Mattyj,

I absolutely love your CalTopo and have been using it for a while. Recent I've run into a problem when I try to edit point markers. I get an error and the map is not saved:

"Server Communication Error! Data may not be getting saved properly, reloading this page may solve the problem. This message will not be shown again until you reload the page, but the problem may persist"

I can delete existing markers and add new markers. I can edit and save changes to lines and polygons. I know it was working. Any help forums that would be a better place to seek help?

Thanks,
Mike

There's a forwarded email address on the "About CalTopo" page that's likely to get my attention sooner. No help forum, though.

This was an unintended side-effect of a change I made over the weekend that allows you to edit a marker's coordinates. It's a pretty large/embarrassing mistake to have slipped through my testing, but these things happen. Thanks for the heads up and it should be fixed now.

Holy smokes! That is better tech support help and service than I get from my paid vendors! Best support ever I've ever gotten in fact
I am planning a trip to Alaska with two other folks that I introduced to your tool. Caltopo rocks for this type of collaborative planning. Thanks a million.
Mike

Just another vote -- this is a great resource, Thanks!

I was just struggling with my old National Geographic California Topographical Map program and CDs (that I paid for several years ago) this weekend, saw this posting, and got the map data I needed much more quickly and easily. I've already shared this website with several other people - it's a great service!

I agree it is an awesome resource. I particularly like the Land Management overlay data.

Matt, is there a way to easily see the elevation at a given point on the map? Topo! does this along with lat/lon information, but caltopo seems to just provide the lat/lon info by default in the upper right corner.

Thanks guys.

Bob, you're not the first person to ask about that. You can right click on a point and choose Point Info | Position and Elevation, but that's probably slower than figuring it out from the topo's contour lines. An instant elevation readout under the coordinates is on the to-do list, but first I have to figure out how to pull a grid of elevation numbers back from my server without slowing things down too much.

One question is how much horizontal accuracy I need. I probably don't need to update the display every time the cursor moves a pixel; every 2nd pixel should be enough. If I could get away with every 4th pixel, that would seriously cut down on the amount of data I'd need to pull back every time the map moves. It's hard to see exactly what the hand's centered on anyway. Any strong opinions?

I gotta say, since I discovered Caltopo a few months ago, I have thrown my Nat Geo Topo in the recycle bin!!! Great job!