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Mapping

Show Profile  Bryan Posted: 3 February 2011, 8:57 AM  
Looking at the sprint specifications again, I think it becomes clearer.

We have some options to map urban gardens -
1. by runnability (white, light green to dark green)
2. Impassible vegetation (100% green, 50% black)
(an area of DENSE vegetation which is impassible or shall not be crossed, due to forbidden access or because it may constitute a danger to the competitor. Competitors disqualified if they go through these areas)
3. Forbidden access area (Olive: 100% yellow, 50% green).
(an area with forbidden access such as a private area, a flower bed, a railway line etc. Competitors disqualified if they go through these areas)

Using these definitions, there is little I would change on the Ben Burn map - most of the fight vegetation is actually fight (eg flax bushes) and wouldn't really be damaged if a cazy orienteer wanted to go through it. What I would change would be to show the flower beds (where plants could be damaged) by olive green. I actually did this on the Central Park map.

In regards to other comments:
- since running on an ACT map after running on a Steve Key map, I've been against too much generalisation and I think its always better if you can to show a feature by a shape rather than by a point symbol.
- I think little would be required to change the map to make it conform to IOF sprint (1:4000 or 1:5000) - it just requries in a few places to clarify or generalise - done by just producing a print at 1:4000 and working on the areas which are too detailed - this exercise would only need to be done if a map was used for an A-level or IOF event.
- checking the printing ghosting that occurred on the event map - this definitely doesn't occur on my laser printer at work which is why I didn't pick it up when I did a QA and test print after drawing was finished.


Show Profile  Michael Posted: 3 February 2011, 8:15 PM  
Elsewhere Jason wrote about transparency "... Michael tells me..."

I don't fully understand transparency in OCAD, and they were only theories Jason. It would be good if anyone who knows more were to enlighten us.

But what I THINK is this: in offset printing one colour goes onto the paper first, and then the other colours. There is some "show-through" of the underneath colours. In digital printing, each pixel is usually only one colour - whatever is top in the OCAD colour table. This allows the cartographer to take shortcuts: where green overlaps yellow for example it is the green that will be printed.

Now the IOF seems to be wedded to offset printing. So the good people at OCAD have provided a way where that pixel can be a combination of the top colour and the ones underneath it. Funny thing though, this transparency notion has only appeared recently and I doubt whether anyone would accidentally use it without deliberately choosing it.

I've always been nervous about overlaps working properly. I like to use curve following to abut areas of colour, and cut holes and fill them rather than just superimpose. But there are ALWAYS overlaps eg contours over green and yellow, and its a bit of a worry if one printer handles these things differently from another:-((

Show Profile  Bryan Posted: 4 February 2011, 8:45 AM  
The map printed for the event was A4 (I produced an A3 version which covers a bit more area) so some export and editing was done on the event map.

I think the event map has a different colour table which doesn't cut out the yellow over green.

The event map also left out the Wellington City Council requirement that the map has to show a note that the contours/curbs and building outlines were owned by them and not be used for engineering purposes.



Show Profile  Bryan Posted: 4 February 2011, 9:22 AM  
From an email to me from Michael:

"Ive got this wrong before so I proceed tentatively but... are all the symbols the right size? For example the black crosses should be 1.2mm and they seem under a mm to me."

Yes, Michael is right - I mentioned above that the contour lines were smaller and other symbols are smaller than the standard.

This came about because of the different requirements for the mapping and not checking the symbol sizes for the export Ben Burn map from the Master map.

I'm still experimenting, it's a work in progress and I'm happy to say I'm still learning my trade after 30 years mapping especially for sprint maps.

For the area in question, I actually fieldworked at 4 different scales (1:5000 Karori Streets, 1:2500 Karori Bush and parks, 1:1000 schools and university buildings and grounds, and 1:500 for The Maze)

I also created maps at different scales as well (1:3000 Ben Burn, 1:2000 Samuel Marsden, 1:1000 Karori Normal School and The Maze offset shown on Ben Burn Map, and 1:500 (The Maze). The symbols that ended up on the Ben Burn map were symbols used for the 1:1000, 1:2000 maps - the Ben Burn map requires new symbols to conform to the IOF standard and some generalisation to get the best readibility for a 1:3000 or 1:4000 version.

I'm happy with the level of detail I've mapped - it just needs some tweaking to get the right symbol size and the right clarity for the right scale. It's an art rather than a science.

I welcome any thoughts on how to cater for all the requirements - printing from 1:500 through to 1:10000 using the same master map. Some GIS systems use pyramid capable software showing different symbols/shapes at different scales for the same feature but Ocad can't handle it.


Show Profile  Michael Posted: 4 February 2011, 12:39 PM  
I think you're under-estimating the task of making a (say) 1:4000 version Bryan. First you have to increase a lot of symbol sizes. Then with the scale change a given little courtyard with planter boxes and zig-zag concrete edges is going to have to fit onto a paper area 0.75X0.75 ie 56% of what it does now.

The simplification really ought to be done when you're fieldworking. That's behind the exhortation to fieldwork traditional maps at 1:7500. (Which I no longer do but I managed until my eyes were 55yrs old.)

I met this problem in creating the 1:20,000 map of the Wellington region that we use for MTBO and rogaines. Initially I thought I could plug in existing maps that I had, change their scale, and fiddle them a bit. A, it takes forever. B, you NEVER take out enough when you go to a smaller scale, because the default action is "leave it in". And the "bittiness" looks terrible. I would now use a more detailed existing map as a background and redraw what I wanted, so that the default action is "leave it out". The redrawing helps simplification as well, for example a building with a tiny nick out of the corner is re-done as a rectangle, whereas getting rid of the nick by editing is really really slow.

The "multiple requirements" issue is much wider. Might talk about it later.


Show Profile  Michael Posted: 4 February 2011, 9:38 PM  
Interesting discussion on Nopesport about an urban mapping conundrum: the bridge where you can pass underneath anywhere, not just on a defined road or path.

http://forum.nopesport.com/viewtopic.php?f=1&t=11291

Show Profile  Selwyn Posted: 6 February 2011, 1:43 PM  
With respect to sprint maps, Bryan quoted the mapping specs:

"We have some options to map urban gardens -
1. by runnability (white, light green to dark green)
2. Impassible vegetation (100% green, 50% black)
(an area of DENSE vegetation which is impassible or shall not be crossed, due to forbidden access or because it may constitute a danger to the competitor. Competitors disqualified if they go through these areas)
3. Forbidden access area (Olive: 100% yellow, 50% green).
(an area with forbidden access such as a private area, a flower bed, a railway line etc. Competitors disqualified if they go through these areas)"

I still find this a little bit confusing, but my interpretation is that:
Symbol 421.0 (100% green , 50% black) should be used only for forbidden areas that are dense vegetation or dangerous.
Symbol 527.1 (100% yellow, 50% green)) is for any other area that is forbidden, presumably any place or vegetative area that on the terrain appears crossable.

I have used 421.0 in a city park map. This was close to black symbol and when printed was very hard distinguish from black, especially at running speed. I guess you could argue that the more we use these symbols as per IOF rules then the more orienteers will get used to reading them which only good for us when we compete overseas.

And I have just noticed that part of this has already been discussed on the Close to Home thread!


I think I raised this before:
I still can't come to terms with the usage of urban and non-urban brown. If both are used on the same map the map looks a bit messy. Maybe IOF never thought we would combine some urban bits into non-urban maps. Every map I have run on overseas sticks with one shade of brown for all paved surfaces and possibly also for unpaved paths. The 0.07 black line defines any changes perceived on the ground.

Selwyn



Show Profile  Michael Posted: 7 February 2011, 4:46 PM  
Selwyn wonders if IOF didn't think we would have urban and non-urban on the same maps. Yes its pretty clear they DID, read the sections on paths and on paved areas. But I agree its very odd. Especially the lack of guidance on the shade of brown to use which can be anywhere (for urban areas) from 30% to zero. Doesn't zero percent brown look rather like runnable forest?

But Ross Morrison in discussion has said that he likes the brown sandwich tracks, they jump off the page at him. He suggests that some of us have with a lot of years of looking at black dashed lines might just be slow to adapt. That's a valid point of view.

Show Profile  Sandgroper Posted: 5 March 2011, 3:03 AM  
Just wondering what people think about the passable wall symbol in ISSOM. I'm currently mapping an urban area that has a lot of low walls from .25m to 1.0m high. The passable wall symbol at 0.35 seems just too big for these features, especially as some of them are quite close together. I am considering using the passable stone wall symbol which is only meant to be used in non-urban areas - any thoughts?

Show Profile  Michael Posted: 6 March 2011, 6:00 PM  
The rural stone wall symbol has blobs which are 0.6mm dia so if you have a problem with things close together this might be worse. You could reduce the problem with the 0.35 lines though by forgetting about walls only 25cm high.

You don't say whether these are single-sided (retaining walls) or double-sided walls. And the specification IMO is deficient in using the same symbol for them both, as a competitor I would like to know. ISOM2000 is similarly deficient although there I avoid the ambiguity by using the cliff or passable rockface for single-sided walls.

If your very low walls are single-sided, you can use 529.1 step or edge of paved area.

Show Profile  Sandgroper Posted: 6 March 2011, 8:56 PM  
Hi Michael.
There are both single (see* below)and double-sided walls. I tried using a mix of passable wall and the .14 step (529.6) with the cut-off between them set at 1.0m high. I really wanted to set it lower (0.5m) but there are several places with 0.6-1.0m walls very close together, and using passable wall distorts the space between them. Displacing the passable walls to make more space then distorts other detail. Also I want to use some of these 0.6-1.0m walls as control points, which I would not be able to do if they are drawn with 529.6.

Using the stone wall gives the map more clarity. The blobs are not really a problem because they are spaced, and the lines can be cut so that they don't occur opposite each other. And I can use them as control points. I also think they are easier to read on the run than the grey passable wall symbol.

I guess I was following other discussions here (and elsewhere) about using other non-urban symbols (eg paths, paved area shadings) and thought 'why not?'.

* The single-sided walls can be distinguished from double sided ones to some extent with the use of contours, and especially form-lines (ie approx. 1m on a ISSOM map). If you use the cliff symbol, do you include tags? If not, how do competitors know that a short black line is a wall drawn with the cliff symbol? I wouldn't be expecting to find cliffs on an urban map. If there are no tags some competitors might think it is an impassable wall and take a slower route.

In the long term, I would favour ISSOM going with a thinner line and a darker grey for passable walls - say 0.3 with 60% black. I have thought of using that for my map, but I think it would be a more serious departure from the current ISSOM.

Show Profile  Michael Posted: 6 March 2011, 10:14 PM  
If I use the cliff symbol.... I was talking about ISOM maps there not sprint. Yes many of the sprint decisions spring from the choice of the thick black line for a barrier, and hence several other black symbols have had to be avoided. They've forced us into a situation where we need to distinguish, on the run, a thin line from a thick one, and perhaps subtle shades of gray, to tell whether we can pass or not. For those of us using digital printing, not good.

This place you're mapping, with lots of passable walls closer than 2.5m apart, is it some sort of maze?



Show Profile  Sandgroper Posted: 7 March 2011, 5:27 PM  
I'll send you something by email - is your AP address still valid?

Show Profile  The Map Guy Posted: 15 April 2011, 12:09 AM  
The latest update for OCAD 10 has just been released (10.4.09)

Show Profile  pcbrent Posted: 17 May 2011, 9:54 AM  
Can anyone tell me if it is possible to import a .sid or a .ecw file to use as background in OCAD?


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