As usual the list solved my problem in minutes after it had been sent.
Thanks to all those who replied.
The solutions varied from using a grid, converting the grids to rectangles
and then to regions and to use grid thermic mapping.
The solution I have gone with is Jacques and Jason's to create rectangular
(or Sheila's suggestion of hexagonal) regions and still use normal thermic
mapping. I was worried that the redraw times might be slow but they appear
to be acceptable in this application.
Thanks very much to all who replied!
Jim
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*****************
Along the same lines as Jacques suggestion, you can create a rectangular
polygon around each point in just one command line statement...
update YourTable set obj = MBR(buffer(obj, 12, 10, "km"))
Make sure to use a copy of your point table as this replaces the dots with
boxes. The 12 is the "smoothness" of the buffer, you shouldn't need to
change this. The 10 is the radius in kilometres. You would change the
statement to read 1.5, "m". Then you can thematically shade all those
polygons however you like. Like Jacques said, you may want to select them
all and Object>Convert to region so that they behave properly when changing
the projection of the map window.
FYI: The excellent 'Discover' add-on from Encom (www.encom.com.au) also has
that option when creating a "surface" from points like yours.
Regards,
Jason
____________________________
Jason Adam
GIS Specialist
De Beers Canada Exploration Inc.
Toronto, ON
[EMAIL PROTECTED]
www.debeersgroup.com
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Sounds like a grid thematic would suit your purposes pretty well (assuming
you have MI Pro v5.5 or later).
The grid thematic is easy to generate and can be modified in a similar
fashion to other thematic styles. Of course it will give you a completely
filled layer (with the option of translucency) rather than "just about
overlapping" points, and it will also give a very smooth appearance (which
may or may not be what you want).
Another way would be to Save Window As for your points thematic, but then
you'd have to register the resulting raster, and you wouldn't be able to
change the settings without saving another raster.
Best Regards,
Martin Higham
Avantra Geosystems
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****
If you are not too concerned aboyt getting a perfect topology you can try
the following route: (use the MapBasic window when needed)
Make a copy of your table as (yurtatb ???)
Make sure you work in your table projection
Set coordsys table yurtab
Transform points into lines (1.5 is half the distance between two points,
could be different in X and Y) (the distance should be expressed in the same
units as those used in the coordsys, meters for ex.)
Update yurtab set obj=createline (centroidx(obj)-1.5, centroidy(obj)-1.5,
centroidx(obj)+1.5, centroidy(obj)+1.5)
Transform these lines into rectangles
Update yurtab set obj=MBR(obj)
You can work with these objects but if you change the projection it is
advised to change them into regions, if not gaps and overlaps can appear.
Update yutab set obj=converttoregion(obj)
Nb the last two steps can be combined into one set obj=converttoregion
(mbr(obj))
I often used such "cellmaps" and found that when setting the border style of
a thematic map to nil, one could get pretty nice and fast results.
Jacques Paris
e-mail [EMAIL PROTECTED]
MapBasic-MapInfo support http://www.paris-pc-gis.com
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*****************
Hiya, not entirely sure what you need. You've got an
overlay of points which contain attribute data right?
Now I'm guessing when you look at the mass of points
you get an overall "picture" of whatever it's meant to
show? Why do you want it in raster format? If you
really needed it in raster, you would need to save
window as [under file], and copy it back into
mapinfo...you could then register the raster image to
fit exactly over your point table..but that's all
you'd be able to do with it.
Raster images contain no attribute data, so creating a
thermatic map won't work because there are is no
attribute data attached to a raster image (just
pixels).
Also, redrawing the points is quite slow? How often
are you redrawing the map?
I'm not sure I'm answering your question as you
hoped...Feel free to correct any assumptions I've made
that are incorrect.
Good Luck,
Ben
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You could make a grid using the grid maker tool (with closed regions as the
object type) which sits centred on your points.
If you then join the two tables where the point objects are contained by the
grid region objects using SQL select:
select: *
from Tables: Regions, Points
where Condition: Region.obj contains Points.obj
This would give you a table of regions with all the atribute data from the
points table. You could then create thematic maps on this.
HTH
Ollie.
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*******************
Why don't you create a grid/graticule or alternatively create a network of
interlocking hexagons. This way you will be able to "recreate" the look and
feel of a raster framework whilst maintaining the "vector" attributes and
data handling.
You will find tools available on www.directsmag.com for grids/hexagons.
Good luck.
Sheila Quan
Steer Davies Gleave
28-32 Upper Ground, London SE1 9PD
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***************
Try using the "Grid thematic" option and set your cell (pixel) size to 3m
or should it be 1.5m..??
That relies on a numeric value for your attribute....
I am trying to guess what you want to achieve here!
Regards
John Ievers
CDR Group
www.cdrgroup.co.uk
> -----Original Message-----
> From: Jim Wilson [mailto:[EMAIL PROTECTED]]
> Sent: 07 February, 2003 11:00 AM
> To: MapInfo List
> Subject: MI-L Grid points to raster image?
>
>
> Hi all,
>
> As usual I'm in need of help!
>
> I have a table of regularly spaced points. The spacing is usually
> 3m in the
> X and Y direction. Each point has various attribute data and to
> display the
> map of the attributes I am currently making a thermic map of the
> points and
> sizing the points so that they meet but don't overlap to give the
> impression
> of a raster image. Obviously this is not perfect as the redraw times are
> slow and I have to use the display override to change the size of the
> points.
>
> It seems to me that I have basically a raster image there and MapInfo can
> display raster images. Does anyone know how I could display this table of
> points as though they were a raster table and preferably still colour them
> using thermic mapping. Hopefully this way I would get faster redraw times
> but still retain the ability to make multiple thermic maps of the
> different
> attributes of each "pixel"
>
> Anyone got any ideas?
>
> Jim
>
>
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