Map Making 'Industry Standards'

[Avon]

First of all thanks to everyone who offered help and advice.  I’m happy to report that it seems as though i’m making a map that will not only look kinda cool, but should work too!

However now that I’m becoming a bit more familiar with QGIS, I wonder if there may be some industry standards that are better thought out than my “that looks kinda cool” technique.

Eg.
Hwy/Road/track/river/creek line thickness
Label text sizes in relation to city towns, roads, waterways, forests, lakes, areas of interest, etc

Also
When/how to make these roads, waterways, or areas of interest visible at particular zoom levels.  Is this a matter of keeping your map looking clean or is there more of a ‘science’ to it?

And finally
I feel as though i’d like to view just a symbol when zoomed out (a train station for example) but then make the label appear as i zoom in.  I thought i could achieve this by duplicating the layer, but that makes me wonder if the “pro’s” would want to keep the least amount of layers possible, which got me thinking about…

Industry Standards 

I’m particularly interested in peoples views in relation to my map (a 10m topo to be printed) but would also love to hear opinions about online/offline, even raster resolutions etc.

Cheers,
Avon

[Boyd]

IIRC, you are not in the US. But I like the standards that the USGS has established: http://pubs.usgs.gov/gip/TopographicMapSymbols/topomapsymbols.pdf

I can't imagine there are any "standards" relating to zoom levels, although you could look at the different "flavors" of USGS maps and see how they represent the same objects on the 1:24000, 1:100000 and 1:250000 scale maps. If you are making maps for use on a phone/tablet, I don't know that these are relevant.

You could also just look at how detail is depicted in Google maps, they zoom in the same increments as other web and smartphone maps. Here are the scales that correspond to the standard zoom levels.



I approach cartography like any other visual art and use my own judgement for the amount of detail and object size. I like the fact that my maps look different from others. But not everyone shares this philosophy.

I think you need to decide how you will distribute your map. Do you just want to offer a qGIS file? Or do you want to use it with a specific app? Unless you are offering the qGIS file, I don't think your question about layers is relevant. You need to construct the map file in a way that the correct level will display when the user zooms in and out in the app that you choose.

[jolly47roger]

When you say 'scale' for a digital map it is important to remember the pixel pitch/density of the device being used.

For example, at zoom 15 each tile is about 1222 metres East-west at the equator - so 4.7 metres per pixel. If that is on a 'standard' 96dpi display the scale is about 1:18000 as in the table.

Display the same image on a modern smartphone at 450dpi and the scale is 1:84000

[Boyd]

True, the new smartphones with full HD (1920x1080) screens can be a bit of a problem - images are often displayed as though they were on a big computer screen instead of a 5.5" phone. The app makers have not sorted this out so well on the new iPhones like mine (6s Plus), and not only are the maps themselves small, some of the interface elements, like buttons and text boxes, are also very small.

I compensate by scaling objects and text on the map larger, but then the map elements can be oversized if viewed on a tablet or computer screen. Some of the software has a menu setting that allows you to enter a magnification number that enlarges everything to compensate for this. I believe the Oruxmaps has this on Android. Unfortunately, my favorite iOS app, Galileo, doesn't offer this. IIRC, TwoNav has this option, but has some other interface scale issues that I don't like.

[jolly47roger]

Garmin Maps define zooms by the 'bits per coordinate' field for the IMG file.

I work on this being 8 higher than the 'slippy' zoom level - so bpc 23 = zoom 15. As bpc is limited to 24 this means Garmin Maps can't  have more detail than (the equivalent of) zoom 16.

Also, with slippy maps based on a Mercator projection the scale varies with latitude. At latitude 45 the scale is 30% more

[Avon]

Sorry for the slow reply guys, but thank you so much!

Jolly Roger - your info has been filed for a later date.  I know it's juicy but is far over my head at this stage.  Please don't hold back though.  You now have me thinking about an app as this was originally a print only project.

And Boyd what can i say... THANK YOU SO MUCH for your help and time with this!  Such incredible info.  My better half says I owe you one and i think she's right.  I'll definitely be hanging around for a while as my new 'obsession' isn't allowing me to think about much else at this stage. 

However think i may have peaked a bit too early as i'm still missing some data that, which i actually thought was going to be the easiest to acquire eg. towns and cities! After several crappy data sets i managed to merge a .csv file containing census and locality info, only to find the location data isn't accurate.  Killing me...

Anyway this site has got me this far so i'm going to continue to treat everything i learn for now as gospel. 

BTW my maps are looking a hell of a lot nicer due to me taking some 'hints' from USGS link.

Cheers,
Avon   

[Boyd]

Happy to help, and glad to hear that you're making progress.

[Boyd]

Jolly Roger - your info has been filed for a later date.  I know it's juicy but is far over my head at this stage.

Maybe I can point you in the right direction…

With a paper map, the scale represents the ratio of an object on the map to the same object in the real world. This is expressed in the form 1:24,000 which (in our Imperial System) means a one inch long road on the map would be 24,000 inches long in the real world (2,000 feet). Maps at 1:24,000 scale are called "24k maps" here in the US, which is a standard the USGS started using during the early 20th Century (based on what I've seen in the USGS archives).

But the whole concept of "scale" has gotten more complicated with computer devices that display images on a screen instead of a printed page. You need to consider the screen size and how many dots it displays per inch. As a mapmaker, it's virtually impossible for you to know what size screen a user might have. My iPhone has the same number of pixels on a 5.5 inch screen as my 46 inch television for example. There's no easy solution for this, and I suspect it will only get worse since hardware is evolving and screens are getting more pixels, while software isn't really keeping up with this.

Now if you look at the zoom scale list I posted, that shows the equivalent paper map scale, for example level 15 is about 1:18,000 (18k) which would be the closest to the USGS 24k standard. This is what I am currently using for my smartphone topo maps maximum scale.

Now each "click" in zoom levels doubles the map scale, so level 16 would be about 1:9,000. Map files start getting very large when you get into this scale, and it is far more detailed than any paper maps that would have been created for any large area, such as a state or province.

Remember, document size and file size are squared functions, because they represent area - when you double the scale, you quadruple the file size. So if your level 13 zoom scale map is 10MB, then a level 14 map of that same area will 40MB, level 15 will be 160MB and level 16 will be 640MB. When you combine these into a map for a smartphone, you add all of the included zoom levels to get the total file size.

[Avon]

Congratulations Boyd - you've just earned yourself a printed copy of my map! Once it's ready that is...   

Thanks for the explanation of the digital zoom levels.  What does stand out to me is the 1:72, 1:144 etc.  I guess Google are talking 1:72dpi here? That would make sense to me, but the ,223.822090 following i'll just put down to either very logical, or very clever math.  When the time comes, i think i'll just follow that lead and see how it looks on various devices, then i will go for a 1:25k for a printed copy as i'm in Australia.

I'm trying my best not to bombard you with questions, but at this stage you guys are my only contact with the map making world so please excuse me if i get a little carried away at times.

Do you have any maps uploaded to this site that I could download and take a look at on my phone/ipad?  Also I don't suppose you've created an app before?  Yes, i'm getting that far ahead of myself already.  Gotta love a challenge...

Cheers,
Avon

[Boyd]

This site only hosts maps in Garmin's format, you won't find any maps for smartphones here.

I have not made any of my smartphone maps available to the public yet. They are very large files and only work in a specific app. Eventually I will get around to finishing the website I started awhile ago. Here is a small map that only contains one zoom level, it's a .kmz file that works in Google Earth (or any program that reads .kmz files).

IIRC, I created this map at 6 feet/pixel so it would be displayed at zoom level 16. The shaded terrain was created with high resolution LIDAR data. In the US, this comes from the 1/9 arc second National Elevation Dataset.

Download link is here: http://boydsmaps.com/download/boydmap_wharton_30.zip

I have attached a screenshot.

[jolly47roger]

I do develop smartphone maps. For a distribution format I've settled on SQLITE as that can be used directly by Back Country Navigator, Locus and Maverick on Android also Galileo and Mapplus on iPhone/iPad. But Mobile Atlas Creator (mobac.sourceforge.net) will read the SQLITE files, allow you to view them and output to a whole range of formats.

There is a sample here : http://www.the-thorns.org.uk/opendata/opendown.html

[Boyd]

True, the new smartphones with full HD (1920x1080) screens can be a bit of a problem - images are often displayed as though they were on a big computer screen instead of a 5.5" phone. The app makers have not sorted this out so well

Here's a perfect example of this problem. Galileo just offered an update to their iOS app, the first one in some time now. They fixed and improved some things, but they also changed the scale used to render the different zoom levels on my phone. Offhand, it looks like they are using pixel-doubling - treating my 1920x1080 screen like it was actually a 960x540 screen and using 4 pixels to represent one pixel in the image.

It doesn't have much effect on a plain raster image (like aerial photography) but has made a real mess of my topo map that contains 4 different maps for display at levels 16, 15, 14 and 13. I tried just shifting everything up one level (so the map contains levels 15, 14, 13 and 12) and that makes the map the same size it was before but the rendering is ugly.

Am going to have to play with different source resolutions for each map layer and see how to fix this. Ugh, this could take awhile to re-render some big files. 

[jolly47roger]

Back Country Navigator has something similar but at least it is an option to switch on and off and comes with a warning ; "Not recommended, Will make map more pixellated, May allow you to read more text"