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New Hypsometric Ramps for OCAD DEM Based Maps

Hypsometric tinting ramps expand

OCAD DEM colour ramps image
OCAD DEM colour ramps

The mapper of smaller scale maps such as trail maps, may be interested to know that three new colour ramps have been added to the hypsometric tinting choices in a coming OCAD update. One ramp allows choice of colours in up to 10 bands.
 

 

Brown – Yellow colour ramp

Brown - Yellow hypsometric image
Brown – Yellow hypsometric

Brown (high elevation) – Yellow (low) offers a ramp similar to that of the Sustrans UK touring cycle maps. It is easy on the eye yet effective. The ramp in the image is at 50m intervals on a 1:100,000 scale map (and like our Spa Country Explorer trail maps, it is printed on Pretex).

Research shows that many users of hypsometric tinted maps think that colours have meaning for ground content as well as elevation. For example a tint that has green at the lowest level implies to those users that the green also represents forest or farmland. Therefore there has been effort to avoid colour ramps that could give rise to such confusion.

On the full map of the Brown – Yellow image, the cartographers have added a green overlay for specific forest sections. Those are not large areas so it does work well. (See Shaded Relief website below for an article Evaluating Cross Blended Hypsometric Tints)

Red – Yellow colour ramp

Lerderderg Red-Yellow ramp image
Red-Yellow hypsometric

While Brown – Yellow colour ramp tends towards subtle, Red – Yellow is striking yet not glaring. The ramp used in the image is per 100m on part of an 80km trail trial map. The yellow is the Lerderderg Gorge (VIC).

I also trialled showing 50m contours on this 100m ramp. It may well be useful for less expert mountain bike riders who may be more conscious of elevation change when planning trips.

Colour yourself purple

The Greyscale Interval colour ramp is very useful addition. It produces a greyscale 10 segment ramp with each segment at your specified contour interval.

Using an image processing tool you can select each greyscale level in the resulting TIFF background  file and change to a colour of your choosing.

After processing a segmented greyscale, I started up the ubiquitous IrfanView (free but well worth a donation). Sure enough, I found it had the ability to easily select a greyscale and change it to another colour. Below is the before and after image I generated using this process. Not a colour ramp you would use for real but you are welcome to add it to your art collection 🙂

Selectable hypsometric tints OCAD & post-OCAD image
Selectable hypsometric tints OCAD & post-OCAD

Further reading

For those interested in exploring hypsometric tinting specifically or shaded relief generally, then these two websites are good resources.

Shaded Relief website

Relief shading website Some superb hand drawn relief shading including an example produced during 1838-45. I learnt that DEM based relief shading is termed Analytical Relief Shading.

Jim’s Cartography website has some viewable maps that use relief shading effectively without including contours. Jim Lewis is a NZ  OCAD user.

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Book Review – Cartographer’s Toolkit

Cartographer's Toolkit book

Colours, Typography, Patterns

A toolkit it is. Supposedly only for those who have expert cartographic knowledge. I cannot lay claim to the latter (my only career regret), yet I am finding this toolkit very useful. In fact it lifted a mental block for me on one map. So unless you are a pure orienteering mapper, this toolkit is likely to have tools that you can reuse for both print and web cartography.

I have already reused colour palettes, acquired new fonts, used one composition pattern and admired the abstract art. Exactly as Gretchen N Peterson intended in her book Cartographer’s Toolkit | Colors, Typography, Patterns. She has carefully thought out and very successfully presented the chapter elements.

Colour Palettes

Colours sample
Colours sample

The Color palette chapter presents a series of harmonic colour sets. It encompasses coordinated, differentiated and colour ramp palettes. I lack colour smarts so this chapter has been a boon, enabling me to quickly test three likely colour palettes for a new trail map. Each of the 25 or so palettes comprises specifications of 10 colours, samples of usage and even a colour blindness simulation. The chapter is introduced by basic colour theory and practice.

Typography

Typeface sample
Typeface sample

Similarly, the Typography chapter is introduced by the basics of typography in cartography. While I knew of typeface x-heights through my print industry experience, I wasn’t aware of their relevance to cartography. Replacing OCAD’s default font Arial with a cartographic font, I was startled at how much better it looked on the map.

Fifty typefaces are listed across categories of standard (system), free and ‘for fee’ fonts. As with colours, each font is portrayed in a sample situation as well as alphabet and text. Some of these fonts are referred to in my previous post Cartography Typography for Neophytes.

Patterns

Pattern sample
Pattern sample

The signal to noise ratio of the Composition Patterns chapter was far higher than I expected. At first glance I thought the chapter interesting but not too relevant to trail maps. How wrong. Applying a discontinuous frame to an orienteering event map enabled a useful bulge of content to be kept and the map still looked good.

Then line highlights provided a new slant on marking trail routes. Small multiples reminded me I could show enlargements of selected trails on some trail maps. And I really enjoy the intentional and unintentional art.

Maps show the way

And so does Gretchen Peterson. She has resoundingly accomplished her objective of providing tools for reuse. She has also given me pleasure in reading, re-reading, examining detail and re-examining.

In addition to her intended audience, I commend this book to amateur cartographers like myself who have an interest in improving. I cannot close better than by quoting from her introduction

This book enables the thinking cartographer to use colors and fonts deliberately, and it shares ideas for creating just the right layout compositions with just the right elements to create truly communicative and enduring maps. — Gretchen Peterson

Cartographer’s Toolkit | Colors, Typography, Patterns. Gretchen N Peterson. Published 2012 by PetersonGIS. Amazon US$35.

Gretchen Peterson’s informative blog A Cartographer’s Toolkit.