Double your fun with map sync!

[Boyd]

It's two.... two... two maps in one!

Ever wished you could see two maps at the same time? This little web app will have you seeing double! It's is an idea I've been thinking about for awhile, so I threw together a beta version. Choose a map from each menu and they will move in sync. The zoom settings are independent, so you can (for example) have a topo on the left as an overview and zoom way in to an aerial on the right.

There are lots of possibilities, like identifying features on LIDAR imagery.

https://boydsmaps.com/sync/#17.00/39.230573/-74.912595/midatlidar/0/0/pines2020/17.00/0/0



Or comparing aerials from different years. To make the maps more useful, they appear side-by-side in a wide browser window or stacked above each other in a narrow one.

https://boydsmaps.com/sync/#15.00/39.822750/-74.893105/njgin1980/0/0/njgin2020/15.00/0/0



You have the full set of boydsmaps imagery with the exception of Mapbox maps, so no 3d view. I may change this in the future to allow full 3d capability though. Will probably add some other features too. But for now, it works and you can link to any view. For some reason, this doesn't work on my iPhone... the maps display but they don't move in sync. Not sure what's going on there, but this is really intended for a big computer screen and not a little phone.

This is work-in-progress, so I'm sure you'll find some bugs. But let me know what you think of the idea...

[edit]Just caught one bug where the zoom level was changing when you switched maps. I think that's fixed now - if you had this problem earlier, try reloading the the page. BTW, the NJGIN servers are very slow this evening... nothing I can do about that, sorry.

 

[Boyd]

For some reason, this doesn't work on my iPhone... the maps display but they don't move in sync. Not sure what's going on there

I believe this is fixed now. My code was only responding to actions with a mouse, it needed to also "listen" to a touchscreen. It works, but the menus are quite small, making it awkward to use on a phone in its current state.

 

[Boyd]

Here are a few new features:
The plus and minus buttons zoom both maps at the same time. Map 1 (on the left or top, depending on window size) takes precedence here. So, when you click the plus button, Map 1 will zoom in a notch and Map 2 will be set to the same zoom level regardless of the previous setting. There's also an equals button; it makes the map 2 zoom match the map 1 zoom.

The sharing button has a variety of options.

 

[Boyd]

Some more updates today: added copyrights, cleaned up the user interface a bit. There's also a basic help screen now. As usual, you might have some browser cache issues if you have used the site recently.

 

[Boyd]

Fixed some bugs and added a few more features. There's a map info button next to each menu button now that displays metadata.

Also added a site info button that displays terms of use, software credits and privacy policy. And Map Sync is now integrated into the main boydsmaps app. Just click the Sync button and it will open in a separate browser tab. This feature is only available in the desktop version of the boydsmaps app, although it could be added to the mobile version if there's enough interest.
[update] A Sync button was added to the main menu on the mobile app in 2025.

Usual disclaimers apply about browser cache issues, if these features don't work you may need to clear your cache and/or delete site data. That's about as far as I plan to take this project for now. Let me know if you find it useful, or if you have any problems.

 

[Boyd]

Fixed a problem that could occur when viewing maps with very different coverage areas, such as the HERE aerials (that cover the world) with my LIDAR maps (that only cover South Jersey). If you zoomed out on the aerials and dragged the map to another state, the LIDAR would go completely off-screen and this "confused" the software.

Now, if you try to do that... you can't. There's an invisible "fence" that won't let you drag the aerials beyond the limits of the LIDAR in that example. If you try to go farther, the map will "bounce back". If this happens to you, either zoom back in or switch to a different map that has a larger coverage area.

 

[SuperChooch]

I just wanted to pop in and say not only thank you for this, but thank you in general for Boydsmaps! This has been become a permanent feature of my GIS toy box. I was looking at something last night and woke up this morning and remembered this post and thought, "hey that feature would come in handy for this!". (BTW- incoming separate post on that topic )

 

[Boyd]

Thank you so much! It's great to hear that you're finding a good use for this little app.

 

[bobpbx]

That is really handy Boyd, the way you put the cross marker in and that's it's red colored. Was just comparing the 1930 with 2020, and this reduces the location doubt considerably.

 

[Boyd]

Thanks!

 

[Boyd]

Bumping this old thread to note that I just uploaded a small update to the sync app. You can now control the maps using your keyboard, like the main boydsmaps app. This is something I personally find very useful for scrolling and zooming without messing with the mouse. There's nothing to set, it is always enabled.

I also fixed some bugs that I've been ignoring for a long time. Would like to add a couple other things to the app at some point...

 

[bobpbx]

Boyd, I noticed something today when using split screen view that is different than when viewing a single map. I would not bring it up, but it slows down my map analysis in split view.

Say I have it up, and I want to see what happens to the land over the years, which is something I like to do, to see a change that could affect my report. Let's say I start at the 1980 aerial and then want to move up another year and so on. But when I first choose 1980, the map menu automatically places 1980 at the top of the menu. So instead of just moving my mouse over and selecting 1990, I have to scroll the menu down to see 1990 first, and then select it. I can live with doing that, but if it's an easy fix?

 

[Boyd]

Yeah, the map menu code in the sync app really needs to be updated to be like the main app. Have been putting it off because the code has changed to the point where it isn't as simple as just dropping it into the sync app. Also more complicated because there are two separate map menus. I will be taking a look at this, no promise as to when, but it will be this year.

Will take a quick look at how the menu scrolls in the meantime... might be an easy fix. Or not.

 

[Boyd]

I changed it so that it should no longer scroll to the top when you choose a map (I had to clear my cache for the change to take place). I think this does what you want and makes more sense. Only thing is, I wonder why I intentionally had it scroll before? Might have had to do with how it works on a small screen, like a phone. But did a quick test and it seemed OK.