<div dir="ltr"><div><div>Hi,<br><br></div>Sorry for being slow to give much of a response. I started writing a response but didn't quite finish it.<br><br></div>I think it's great to get the heat map documented in a meaningful manner, so thank you both for working towards it.<br><div><div><div><div><div><div class="gmail_extra"><br><div class="gmail_quote">On 11 October 2016 at 21:04, Willem Ferguson <span dir="ltr"><<a target="_blank" href="mailto:willemferguson@zoology.up.ac.za">willemferguson@zoology.up.ac.<wbr>za</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
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<div class="gmail-m_-1747329299522275993gmail-m_-2151224717242623010moz-cite-prefix">On 10/10/2016 17:34, Robert Helling
wrote:<br>
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<div>On 10.10.2016, at 17:22, Willem Ferguson <<a target="_blank" href="mailto:willemferguson@zoology.up.ac.za"></a><a target="_blank" class="gmail-m_-1747329299522275993gmail-m_-2151224717242623010moz-txt-link-abbreviated" href="mailto:willemferguson@zoology.up.ac.za">willemferguson@zoology.up.ac.<wbr>za</a>>
wrote:</div>
<br class="gmail-m_-1747329299522275993gmail-m_-2151224717242623010Apple-interchange-newline">
<div><span style="font-family:menlo-regular;font-size:12px;font-style:normal;font-variant-caps:normal;font-weight:normal;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;float:none;display:inline">give me a more
precise indication of the unclear areas?<span class="gmail-m_-1747329299522275993gmail-m_-2151224717242623010Apple-converted-space"> </span></span></div>
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It was simply the shire number of references to part A, part B
then again A then C. Maybe the abstract letters don’t help. Could
you use more descriptive names every now and then?
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<div>In the end, it’s not so complicated: The heat map
show how much gas is in the tissues compared to the ambient
pressure, all this as a function of time. Blue colors mean less
gas in the tissue and thus on-gasing, green to red mean excess
gas in the tissue to various degrees and thus off-gassing. Fast
to slow tissues from top to bottom. Lots of yellow and red mean
lots of seed for possible DCS. This is the general idea, the
more detailed version should be obvious from the figures (I
would hope). I would think being less explicit in the text would
help (because the reader needs to digest less information).</div>
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<div>What do you think?</div>
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<div>Best</div>
<div>Robert </div>
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The previous gas pressure graph was pretty precise and I could read
the exact compartment gas pressures from the graph and relate them
to the gradient factor (accepting there was no calibrated Y axis). I
prefer information that is as precise as possible, therefore this
preference. In contrast, for the heat map the colours are more
qualitative, but I still prefer as precise an interpretation of the
colours as possible. Therefore just a general notion of blue to red
is not sufficient. For instance, if I have a deco stage with orange
in it, I want to understand whether the inert gas pressures were
very close to the M-value or not. If the heat map cannot provide
that information, it would not serve any purpose for me. Therefore
my strong preference for a much more explicit interpretation of the
heat map. Because of this, it took me some time to get to terms with
the heat map. In addition, if I have never seen a heat map and I am
reading the user manual for the first time, I would like to have the
full explanation, not only a notional summary. The user manual is
most useful for divers using these facilities of Subsurface for the
first time. If I were that diver, I would have preferred the 'full
treatment'. <br>
I hope my approach appears sane.<br></div></blockquote><div><br></div></div>I think both approaches are entirely sane. I think I'm agreeing with Robert in that I believe the greatest strength of the heat map is that the user can see very quickly, in a qualitative manner, when the greatest tissue gradient of a dive occurs, and which theoretical tissues experience the greatest gradient. Heat maps were used effectively in the Simon Mitchell presentation as a way of demonstrating the effects of deep stops vs no deep stops. The heat maps were used to compare two different dives, which was a powerful comparison without needing to assign numerical values to the colour scale. I attempted to illustrate the concept in the graphic I added to the user manual in commit fbcf4b9bd32a362078c81272e0e96f<wbr>87f1d0f980.<br><br></div><div class="gmail_extra">But I also think that someone interested in the heat map would want to know what the colours actually represent, and for this reason we ought to include the values too. The direct comparison between the colour scale and the instantaneous tissue graph is very helpful, as they are representing the same thing.<br><br></div><div class="gmail_extra">My suggestion would be:<br></div><div class="gmail_extra">- Start the section with a paragraph explaining what the heat map represents and how it works (basically Robert's text), with an example of a heat map<br></div><div class="gmail_extra">- Provide the comparison with the instantaneous tissue graph, and provide a numbered legend for the colours (basically Willem's text and graphics currently in master).<br><br></div><div class="gmail_extra">The legend could be a single graphic, comprising an enlarged version of the colour scale you've already made, annotated with:<br></div><div class="gmail_extra">- label oversaturated / offgassing zone, and undersaturated / ongassing zone down left hand side of the scale<br></div><div class="gmail_extra">- tick marks and numbers for % M value at for example 120, 100, 80, 60, 40, 20, 0 down right hand side of upper part of scale, labelled as "% M value" or "Gradient Factor"<br>- tick marks and numbers for % inert gas value at for example, 100, 75, 50, 25, 0 down right hand side of lower part of scale, labelled as "% inert gas saturation"<br><br></div><div class="gmail_extra">If I get a chance, I will create a colour scale legend like the above, but feel free to beat me to it (or suggest a better idea).<br></div><div class="gmail_extra"><br></div><div class="gmail_extra">This could either be separate from, or combined into, the comparison with the instantaneous tissue bar graph.<br></div><div class="gmail_extra"><br></div><div class="gmail_extra">On a related point, I'm starting to think the ongassing zone should be the % inert gas saturation for whatever gas is being breathed, rather than air. What do you think? Currently, a dive with deco on 100% O2 will show "ongassing" for the fastest and slowest tissues, when in actual fact they are offgassing. I think this is misleading.<br></div><div class="gmail_extra"><br></div><div class="gmail_extra">Cheers,<br><br></div><div class="gmail_extra">Rick<br></div><div class="gmail_extra"><br></div><div class="gmail_extra"> <br><br></div></div></div></div></div></div></div>