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91
Newbie's GIS / Re: Spatial distribution on Kuala Lumpur map
« Last post by Noordin on January 26, 2011, 05:08:48 PM »
Creating a masking layer

1. Click the Show/Hide ArcToolbox button  on the Standard toolbar to show ArcToolbox.
2. Expand the Cartography tools.
3. Expand the Masking toolset.
4. Right-click the Feature Outline Masks tool and click Open.
5. Click the Input Layer drop-down arrow and click a layer or click the Browse button  to choose a layer file.
6. Type the name and location for the Output Feature Class or click the Browse button  to create it.

Using a masking layer
1. Click the Add Data button  to add the masking layer to the data frame.
2. Right-click the data frame in the table of contents and click Advanced Drawing Options.
3. Check Draw using masking options specified below.
4. Click the layer you want to use as a mask in the Masking Layers list
5. Check the layers you want to have affected by the mask in the Masked Layers list.
6. Click OK.
92
Newbie's GIS / Re: Spatial distribution on Kuala Lumpur map
« Last post by hhyoong on January 25, 2011, 05:06:27 AM »
Hi Noordin!

Can you please describe it more detail as I don't really understand.

Can I use the map that i pasted in previous replies?

Is that the boundary line (chocolate colour surrounding Kuala Lumpur) that you mentioned?

If is not how should I draw it?

Please guide. Thanks!
93
Newbie's GIS / Re: Spatial distribution on Kuala Lumpur map
« Last post by Noordin on January 24, 2011, 08:05:02 PM »
You need to have the boundary of KL as a layer. Then used this layer to mask the interpolation or IDW that you carried out.
94
Newbie's GIS / Re: Spatial distribution on Kuala Lumpur map
« Last post by hhyoong on January 22, 2011, 04:15:36 PM »
Thanks for the reply.


Graduate Color


Graduated Symbol


Proportional Symbol

To me, all three above are not spatial thoughtsysis.

However, our main objective is bout doing spatial thoughtsysis on a KL map and produce color contours to indicate the level of parameters as requested by our supervisor. So I think we have to assume that they are spatially related. Let's ignore whether it is adequate or accurate.

Can I know how to fit my color contours into KL map? I don't want it to be out of the boundary of KL.

Please guide. Thanks once again
95
Newbie's GIS / Re: Spatial distribution on Kuala Lumpur map
« Last post by MyGIS on January 22, 2011, 01:17:55 PM »
Hi,

In my opinion the way you are representing your results is inadequate. To show the contrast, you should simply use some qualitative method to symbolize your points. I would assume that you are using ArcGIS Desktop for your work. Go to the layer property , symbology and choose Graduated Symbol or Proportional Symbol method under the "Quantity" group of symbology.

In your method above you are assuming that the phenomena is spatially related somehow for all the restaurants  neighboring the ones you have sampled which in my point of view may not be the case.

Perhaps Noordin may agree.

Thanks.
96
Newbie's GIS / Re: Spatial distribution on Kuala Lumpur map
« Last post by hhyoong on January 22, 2011, 02:24:41 AM »
Hey.

Mostly from restaurants and petrol stations.

Trio of us had done the lab thoughtsysis for 13 elements/parameters as required by our supervisor. What we need to do now is to do the spatial distribution for each single element based on the result into KL map. Therefore, we have to produce 13 KL map with spatial distribution on it.

Pictures below are the one we managed to produce so far based on your guidance.


Original map with the coordinates


This is the one with IDW model.

I'm not sure whether this is the right way. Any idea how to fit the contour into the map instead of rectangular shape?

Please guide. Thank You
97
Newbie's GIS / Re: Spatial distribution on Kuala Lumpur map
« Last post by MyGIS on January 21, 2011, 11:54:02 PM »
Hi,
Do you mean that you go to places like houses offices ...etc , take water samples from taps than thoughtsyze that water?

Thanks.
98
Newbie's GIS / Re: Spatial distribution on Kuala Lumpur map
« Last post by hhyoong on January 21, 2011, 06:42:55 PM »
@Noordin

The water sources are actually from pipe water all over KL.

Do you have any idea which model would best fit the distribution?

Can you tell me what should I put for the Z-value field? Is it my impurities level? And what does the power value means? Assuming that is in IDW mode.
99
Newbie's GIS / Re: Spatial distribution on Kuala Lumpur map
« Last post by Noordin on January 21, 2011, 05:58:08 PM »
First of all I have to declare that I am not an expert in modeling water impurities. However from the general knowledge that I have, the impurities in drinking-water originate from many sources such as sewage, agriculture and urban run-off, industrial wastewater, and chemicals used in the water treatment process, and also the piping.

Just a matter of curiosity where does the samples taken from - the source (river) or the water pipes? Anyway both requires you to know the coverage of the water distribution. That is to say each collection/treatment/storage center covers certain region of water distribution. Within this distribution region they will be correlation/relationship. However it will be difficult to establish relationship between the regions.

Of course a detail modeling will require you to have a distribution pattern too. As such this is totally different approach to the use of IDW to interpolate the "general" overview of the impurities content.
100
Newbie's GIS / Re: Spatial distribution on Kuala Lumpur map
« Last post by hhyoong on January 20, 2011, 08:09:50 PM »
@MyGIS

Ya. I'm using ArcGIS and using the Spatial thoughtsyst  extension in the menu. There's a part where I have to key in the Z value >< (Using IDW). So I was wondering is this the one that decides contour levels.

@Noordin

Thanks for guiding me!

The steps are as below:

1. Adding XY data into a Malaysia Map(from website) with WGS 1984 settings

2. Perform the interpolation using Spatial thoughtsyst. Click the second option on General tab under option menu

3. As for thoughtsysis extent is set to Same layer as Coordinates$ Event which is the name for my excel.

4. Interpolate to Raster by selecting IDW (which I don't know which model to be used but follow the tutorial found on the net). I set the Z-value field as ppm which is my level of impurities. The Power, Search Radius type and etc remain unchanged as I have no idea what it is.

What i get is nice colourful contours surrounded by a big rectangle. How should I really fit into Kuala Lumpur Boundary only?

Is IDW the correct model to be used? Please guide on which model to be used to improve the accuracy.

Thanks.

What model would you suggest in order to provide better accuracy? Please guide.
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