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Mapping

Show Profile  The Map Guy Posted: 28 January 2009, 9:25 PM  
Regarding the bare earth topic: I remember bringing up this topic in 1997 when I had to represent bare earth on farmland.

The bare earth was the result of underground heat (geothermal) which had killed the grass. The ground was perfectly safe to walk/run over. My solution was to use bright yellow with black dotted vegetation boundary. Worked well. Mind you these areas were fairly large and probably didn't need the vegetation bounday shown.

I'm not familiar with the above maps, but for the feature to be shown on the map it has to be large. As Michael said, there is a high risk of the blob being mistaken for a knoll if brown is used.

If 1:10,000 scale dimensions are used to draw a map, then a dot knoll of 0.75mm diameter represents 44 square metres (on the ground). An elongated knoll is probably larger. This approximates to a 7.5m ground diameter. We know that the map dot knoll is exagerated in size.

It stands to reason that the brown "bare earth" blobs must be around four times the area (i.e. 176 sq m) for them not to be confused with a dot knoll. This approximates to 15m ground diameter.

Why four and not two? If you double the size, then the area increases by the square of the dimension increase.

Were those bare earth features that large, or should they have not been mapped? Or should you have stuck to a specially created darkend bright yellow - create by adding extra magenta so it sticks out from the scattered trees/open land symbol.

Show Profile  Selwyn Posted: 28 January 2009, 10:45 PM  
I use Vista Ultimate 64 bit system. There have been comments that 64 bit operating system fails with some software. It has no problems with OCAD-9 and OCAD-10. I haven't opened OCAD-8 since installing my new computer.

Show Profile  Michael Posted: 29 January 2009, 12:00 PM  
Bare earth - I think the black dots would make things quite messy - they don't work very well for very small patches of trees either. I feel we are looking for a solution based on a colour that stands out.

Whatever that colour is, there's a minimum size. Map Guy has approached it from the point of view of being bigger than a dot knoll, but the specification also gives it to us. 0.5sq.mm (at 1:15,000 and of course that's written with offset printing in mind so we shouldn't push this with digital printing!) Assuming a circular patch, that's 0.8mm across, ie 12m on the ground.

Five double paces at running pace. About 7 at my walking (mapping) pace. Same minimum applies to blue, green, grey or yellow full colour. (Large minimum for dotty colours.)

I wonder if OCAD could get a checking function for undersize patches?

Admission: I regularly push the minimum gap between contours, in sand dune mapping.

Show Profile  Michael Posted: 29 January 2009, 12:07 PM  
I just tried the OCAD measure function on a tiny patch. It gives you the area in metres and sq.mm - but only to the nearest 1sq.mm. Anyway, the decision needs to be made in the field. "One and two and three and four and five and six and seven..."

Show Profile  Michael Posted: 29 January 2009, 12:20 PM  
OCAD 8 and Vista, version 10 is nearly here! Among other things, V9 and V10 have much better handling of multiple templates, real-world coordinates, and GPS input.



Show Profile  addison Posted: 29 January 2009, 2:28 PM  
How long are they beta testing for?

Show Profile  Michael Posted: 29 January 2009, 3:58 PM  
It was said to be to 31 Jan. I haven't seen any indication that release would be delayed, but you can't tell with testing.

If you buy v9 during the testing period of v10, you get v10 for no further payment, when released. So v10 is no reason to delay upgrading.

Show Profile  The Map Guy Posted: 31 January 2009, 3:47 PM  
OCAD10 beta version 6 has just been released. It now allows you to export data to your GPS (or to Google Earth). Previously you could only import data from your GPS. Well done the OCAD Team!

Show Profile  Michael Posted: 1 February 2009, 11:46 AM  
Thanks Map Guy. I see that beta testing now continues to 28 Feb.

Show Profile  Michael Posted: 19 February 2009, 2:17 PM  
Couple of little annoyances, wonder if they happen to anyone else.

Failure to automatically redraw after editing. Seems to occur after prolonged use. Cured after exiting and restarting OCAD I think.

Sudden shift of the image on the screen. Not a particular problem except in the middle of a careful template adjustment, when you have to start again.

Show Profile  The Map Guy Posted: 19 February 2009, 4:23 PM  
I haven't encountered the "automatically redraw" problem in OCAD10beta - yet. But I used to frequently encounter it in OCAD versions 7 and 8 after long drawing periods. The solution was to get into the habit of clicking on Optimise/Repair, then Save. Cured the "problem".

Current OCAD10 testing stage is now extended to the end of March.

Show Profile  The Map Guy Posted: 21 February 2009, 1:50 AM  
If you've been supplied with geo-referenced JPG files and you want to tile them together only OCAD10 will allow you to do so (no problems with geo-referenced TIFF files with OCAD8 and9). The really neat thing that I've discovered is if JPG files are imported into OCAD10, then saved as an OCAD 9 file, the images will then import geo-referenced into OCAD9.

So if you haven't upgraded to OCAD10 and have to work with JPEG files give them to somebody who has OCAD10 and they can do the conversion for you.

Note there are two files for each image - the graphic, and a world file (has co-ordinates for that image).
For TIFF files the set have suffixes: tiff and tfw
For JPG files the set have suffixes: jpg and jgw

Note the "set" must have the SAME prefix.

Of course you can always do it the hard way: save the JPG as a TIFF, then change the corresponding TFW suffix to JGW. TIFF files are very large.

I recommend using geo-referenced images if you can get hold of them. Great for Park maps - your Council will have the images. You don't have to adjust the background map/template.

Show Profile  The Map Guy Posted: 3 March 2009, 3:36 AM  
Looks like OCAD 10 has now been released (no longer beta) - right on schedule.

Show Profile  Linley Posted: 4 March 2009, 10:04 PM  
I am mapping a area of young pine forest where trees are 2m high, the gaps huge, and they are growing in very straight lines. As the canopy isn't anywhere near formed I can't really justify usring 411. I feel like using 404 but the trees aren't scattered. Any suggestions are welcome as someone must have come across this before.

Show Profile  Michael Posted: 4 March 2009, 10:49 PM  
What's wrong with 405 Linley?

I'm not sure that the presence or absence of canopy is relevant. A strict reading of 403 suggests that once trees are over 1m high open land becomes "forest", although I'm happier when they're over my head. 411 is only going to come into play if runnability is reduced across the rows, your talk of gaps suggests not.

White forest, lucky you!


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