Print scale bar and web mercator

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4
03-26-2015 06:23 AM
Status: Open
TONIFAIRBANKS
New Contributor III
There is a long standing known bug where the scale bar does not match the map image scale when printing and using web mercator.  This is a major problem and NEEDs to be addressed.
4 Comments
DavidWheelock
Yes, I second this recommendation. The scale bar should allow the option to use GEODESIC calculations for distances. This would always give correct distance regardless of projection. The measure tool offers this option. Why mot the scale bar?! If I were programming this software I would make geodesic the DEFAULT and give the user all of the distance options that they have in the measure tool.
BillFox

Work around:

 Example: We want a 1” = 40’ print out

 40’ * 12”/1’ = 480’

 Take that number 480 and multiply it by 1.25 and enter that number 600 into the Print Widget’s Advanced dialog

by Anonymous User

Where is Scalebar accurate in 3.x JS API?   Scalebar | API Reference | ArcGIS API for JavaScript 3.23  

I had a somewhat related question where scalebar in the API was discussed... Interesting takeaway is "When the scalebar is inside the map, the actual location of the scalebar is used to calculate the scale. "  So, is that not the case on the printout?

I think also that geodesic should perhaps be the default. It seems more intuitive, as an 'accurate' distance, right? Though users may initially be surprised at curved great circle lines, if that was how the measurement line was displayed across the map from start to end. But after a while, it may better inform the public on geography and geodesy. Perhaps reverse the Google 'effect' on the public perception of geography:  (Scalebar on global map, calling aerials satellite, which everyone now calls "satellite view" etc...)   Or perhaps it would create both, the projected line and actual shortest line which may be a curved great circle line if near poles. Esri's devs presented such a viewer at the Dev Conf last year but I don't have a link. Their custom viewer showed both lines at once, while displaying the geodesic true shortest distance in the label text for the distance. I think that would be a good default for measure tools.  Paging Jeremie Cornet.. Jeremie Cornet

I have noticed many GIS analysts, including me until recently, are not aware how the scalebar works, and that not every map should have a north arrow. While Esri has published a few great blogs on this,  (1,2,3,4).    the software has not caught up with it. It is difficult to make cartographically correct maps. While it is too 'easy' to just throw a scalebar and north arrow into a map. It would be good to have a variable scalebar, more easy to create rhumb lines etc. And also should have more user interface warnings to analysts and programmers in projections regarding measurements.   I know, I know... some may ignore them and get 'dialogue fatigue' like projecting-on-the-fly warnings. But it may be helpful.  May also be neat if the JS API could create a Tissot's Indicatrix or something. I came across this and may play with it.  I make county scale maps but for global researchers check this out Making the Tissot's Indicatrices | ArcGIS Blog 

Long story short, I have noticed as GIS becomes more broadly available, things like the infamous Economist example are happening: www.economist.com/node/1788311 http://spatial.ly/2011/01/geographical-mistakes-keeping-geographers-busy/

More geodesy background:

 

blogs.esri.com/esri/arcgis/2007/06/08/does-every-map-need-a-north-arrow-and-scale-bar/

thetruesize.com

www.geography.hunter.cuny.edu/~jochen/GTECH361/lectures/lecture04/concepts/Map%20coordinate%20system...

blogs.esri.com/Support/blogs/mappingcenter/archive/2010/04/21/Back-to-the-Issue-of-Scale-Bars.aspx

blogs.esri.com/esri/arcgis/2011/04/08/making-the-scale-bar-the-right-length-in-arcmap/

 

 In web viewers, measure geodesically-  blogs.esri.com/esri/arcgis/2011/07/21/calculating_geodesic  community.esri.com/groups/coordinate-reference-systems/blog/2014/09/01/geodetic-distances-how-long-i...

blogs.esri.com/esri/arcgis/2010/03/05/measuring-distances-and-areas-when-your-map-uses-the-mercator-...

community.esri.com/thread/23160

Example of a map that communicates scale wisely: https://maps.ngdc.noaa.gov/viewers/hot_springs/ Look at the bar, and when it’s not present. Note also how Google Maps measures distances with the great circle now. (right-click)

I think now that Esri is going 3D it could really be an interesting and exciting opportunity to give the public and analysts more deeper understanding of geodesy.  I look forward to seeing the Measurement talk at Dev Conf this year!

by Anonymous User

Kory Kramer‌ and all - is there any way to deal with this or any plans to better represent scale in print jobs?  Given that most will be in web Mercator and I understand it is not accurate in any of the four dimensions of measurement but I think we could put a note on the printouts explaining this and stating the measurement is geodesic and that would probably be optimal since most users print at a small extent (fine scale). 

A new option was just added to the WebApp Builder print widget; to let users print to any WKID.  Go under the Advanced section and select the Projection. However, it is hard to predict where it will print.  The printable extent should be shown on the main map viewer as a red outline like Larry Stout's PrintPlus, which would help usability.

In fact, I think this is a bug... no matter what scale I try, it ends up waaaay somewhere I have NO CLUE where. Some other state. Looks like a bug? Anyone else see this?  I try WKID 2239 and no matter what scale, somewhere else. Looks like this needs some attention. Engineers immediately want to shift it to an even scale of multiples of 12, hit print, and have an accurate scale bar. For a mapping viewer this is essential.