4 replies to this topic

[RobN]

 SP_TripodProgression.png   479.04K   117 downloads

This map needs some help with symbolization and I'm too far into it to step back and see another route.

The map is of two portions of a wildland fire and a number of "treatments' that had been performed prior to the fire. It accompanies a study of how the areas in those treatments fared during the fire compared to untreated areas.

The background colors of the map are of fire progression (with dates as labels). The colors are from ColorBrewer, except that I applied a 20% transparency in order to let the treatment polygons stand out better.

The large blue boxes are study areas and are mirrored from a regional map that shows the general location of the fire.

The blue boxes and fire progression will be described in a caption.

Where I'm looking for ideas for symbolizing the treatment polygons.

I've used line fill for the treatment polygons, using color, line spacing, and angle to help the reader distinguish the various kinds of treatments.

I'm somewhat limited in the number of colors that I can use by the fire progression coloring; polygons in the yellow-orange-red-brown range potentially conflict. However, because the distribution of treatments is not uniform, I can get away with, e.g., making "thin and sanitation cut" be yellow as there are only a handful all of which occur in a darker area of the progression. Sinilarly, the wildfire polygons in red *mostly* stand out, but a couple fires in the darker part of the progression are harder so see.

The tricky bit was choosing colors for those treatment types that occur across the range of progression colors. I've used black, blue, forest green, and a deep cyan, with different line spacings and angles to help the map reader distinguish. But the forest green is hard to see against the darker colors of the progression, and the deep cyan doesn't standout so well against the lighter colors.

I played around quite a bit with colors to find some that are distinguishable from each other, and while this map may not be best possible combination, it's as good as I could make it in a reasonable amount of time.

But perhaps the line shading isn't the best way to go in the first place. Thoughts?

Many thanks.

[David Medeiros]

The problem this map has is the background data (the fire progression) is taking up too much color space and visual complexity leaving less room for your main data, the treatments. I would start by thinning the fire progression boundary lines to .5 or .25 or even less. Use a single color at different saturations for your fire progression or a color ramp of two closer colors (like the yellow to mid orange). Desaturate all of the fire progression colors to maybe half their current saturation. Remove the dates and create a legend, or make the dates smaller and lighter in color.

Doing all of that will free up space in the visual hierarchy so you will have more freedom to work with symbolizing your primary data, the treatments. Not sure how to direct you on those. I'm not fan of pattern fills but sometimes you have to do it. I would try to simplify the symbolization there. Group some of the treatments into the same pattern with different colors (Clearcut; Clearcut & broadcast burn would both be one pattern but each its own color. Same for Thin; Thin & broadcast). This ill help suggest some continuity between similar treatments.

I might also consider generalizing the fire progression boundaries a little. They are very detailed, probably more so than is necessary for this map. Reducing their complexity will also help the other data stand out.

[DaveB]

Yeah, 8 different categories are quite a few to make distinctive. so my first thought was to organize them. Along the lines David M. described. Use one variable (color, line pattern, whatever) to group like treatments and differentiate those from each other by another variable (for example, if you use color for clearcuts, use line pattern to differentiate clearcut from clearcut and broadcast burn - and then use the same line pattern for Thin and broadcast burn, but a different color, and so on).

I'm not sure what the inner blue border is for. If it's just a part of the neatline I would lose it - you have enough lines on the map as it is and that blue line is crossing over a lot of those, as well as a few of the labels.

I agree with David's suggestion with the "background", to maybe restrict the color ramp and to make it even less saturated. If you do that and go thinner on the lines around each class I think you would be okay with the level of detail. I think the dates might be okay remaining on the map (keeps map readers from having to refer to a legen for that info), but maybe try less "black" - by going to a lighter color/gray and/or a font that is slimmer/lighter weight/smaller?

[David Medeiros]

I think the dates might be okay remaining on the map (keeps map readers from having to refer to a legen for that info), but maybe try less "black" - by going to a lighter color/gray and/or a font that is slimmer/lighter weight/smaller?

Normally I would agree, anything to keep the reader from having to go to a legend is a good idea. But here it seems like the exact dates are not as important as the over all progression of the fire (later vs earlier). Because the progression polygons are so complex and there are many islands of the same date we see dates repeated everywhere rather than once. I think the legend could remove the dates allowing us to see the progression relative to itself but still allow for date reference. Another option would be to label the progression like you would contour lines as in the Somali Pirate map example below. This would probably only work if the progression polygons where greatly generalized, which I think might not be a bad idea.

[AndyM]

Couple of questions for which I don't know the answers:

Is a temporal resolution of 1 day necessary? Would the map be just as useful if you showed 48-hour intervals? It would certainly simplify it graphically.

Are both maps at the same scale? (Only one has a scalebar.)

To simplify the labelling and reading of dates, how about calling 7/21 "Day 1" and just labelling the days as 1,2,3...

Observation: on the right-hand map you have 3 contiguous polygons polygons labelled 7/27