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Messages - Noordin

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1
Newbie's GIS / Re: How to convert bounding coordinates
« on: April 21, 2011, 08:22:24 PM »
Dear Yuyu
I would like to have some clarification on the followings before able to help you on the transformation.
 
a. We usually denote a 2D point by 2 values i.e. either X,Y or N/S, E/W. However I noted that your road and river coordinates has 4 values.

b. Your projected value also has 4 values, and more difficult to understand (is it top left, top right, bottom left etc?).

c. I also notice that the projected value for road is in Cassini (which state is that? are they in meters? ) while your river projection is in RSO. Where do you get the projected value?

NA

2
Newbie's GIS / Re: how set up RSO in ER Mapper?
« on: April 08, 2011, 11:23:29 PM »
Since you are using RSO, thus I presume it is a 2D rectification. What is your source of GCP? Are they in RSO too? Rather than working in two softwares can I propose for you to work successfully with all the rectifications techniques on one software. Once that works and being validated, it would be much easier to "try and test" on the other software since now you already have a baseline data to work and compare with.

NA

3
Newbie's GIS / Re: how set up RSO in ER Mapper?
« on: April 08, 2011, 01:01:22 AM »
I think the problem started when your work seems to be in piece meal i.e. you try to solve immediate problem without looking at the final objective. Can we know what is your objective of the project?

Also, briefly provide us the methodology that you took. Projection, rectification, transformation etc are just processes of getting the data onto a certain reference frame. Frankly I don't understand when you say "RSO parameter to built the kertau datum" ! In map projection you have to define the Datum first before doing the projection and not vice versa.

We hope to help you whenever we can but having short of the objective of the project, we may also be misled by your queries  ;)

NA


4
Newbie's GIS / Re: UTM and Peninsular Malaysia
« on: February 22, 2011, 12:43:58 AM »
You are highlighting a universal problem with UTM projections i.e. trying to project 2 zones on a single projection. They are 3 main approaches currently adopted by users varying from easiest to most difficult.

a. Using the zone which has most data/land area. This is the normal approach by GIS users. The distortion will be most at the neighbouring zone which has less data. This approach is acceptable for mapping of small scale : 100K and above.
b. Reprojecting into another single projection. This is done with another projection acceptable for big areas (e.g. Lambert). This will minimize the distortion and it is most found at the boundary of the two zones.
c. Computing geodetically (2d or 3d). This is the most tedious method and even has been awarded MSc for attempts to do this. Data from both coordinates were computed to match the real coordinate on the earth surface in world coordinate system like WGS84 etc. This is not too accurate when there is no height information - thus the quality will depend on additional information like heights and availability of control points. This is good for scale 1:50K or larger

NA

5
Newbie's GIS / Re: Spatial distribution on Kuala Lumpur map
« on: February 01, 2011, 12:43:44 AM »
For the output, the issue is simply because your output depends on your extreme limit of your sampling point. Thus your data need to be outside the boundary for you to mask the area.

The output value for a cell using IDW is limited to the range of the values used to interpolate. Because IDW is a weighted distance average, the average cannot be greater than the highest or less than the lowest input. Since the influence of an input point on an interpolated value is distance related, IDW is not "ridge preserving".

6
Newbie's GIS / Re: Spatial distribution on Kuala Lumpur map
« 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.

7
Newbie's GIS / Re: Spatial distribution on Kuala Lumpur map
« 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.

8
Newbie's GIS / Re: Spatial distribution on Kuala Lumpur map
« 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.

9
Maps in Malaysia / Re: Forest land use Eastern Malaysia
« on: January 19, 2011, 02:58:55 PM »
If you are outside Malaysia, sorry Mark - we are quite strict in providing Geospatial data to the outside world. However there is no harm contacting the Forestry Department since they do have the data. You may have to follow some internal procedures before it can be taken out. Good luck

NA

10
Maps in Malaysia / Re: Forest land use Eastern Malaysia
« on: January 18, 2011, 05:41:37 PM »
Do you mean East Malaysia i.e. Sabah and Sarawak or East of West Malaysia i.e. Kelantan, Trengganu, Pahang?

For the latter, you can buy the land use zoning from JPBD whcih are taken from their State Structure Plan. Please contact Bahagian Maklumat Gunatanah Negara at JPBD HQ in Jalan Cenderasari.

NA

11
Newbie's GIS / Re: Spatial distribution on Kuala Lumpur map
« on: January 14, 2011, 07:08:27 PM »
If you are using GIS to map the distribution of impurities in drinking water, I think the methodology you are using is too simplistic.What you are doing is base on the assumption that the distribution is linear and can be interpolated and/or extrapolated. In actual fact the distribution of the impurities cannot be modeled by IDW or krigging. This is because impurities of one sample point is not directly related to the other sampling point.

But since your main task is for you to use GIS to show "some form" of distribution, inaccuracy is not only on the methodology but also contributed from the maps and data sources. I could see that you have already got some result but for confirmation, probably you could put to us (or summarize) in 5-10 steps how you have achieve the results.

NA

12
MyGIS , I was looking the way to convert Casini to Lat/Long . currently is using Megallan GPS 200 series .

I presume you are looking for lat/Long in WGS84 since you are using GPS receiver for your work. Also I presume that the Cassini is in the old system.

The old step of conversion is Cassini -> RSO -> Kertau48 -> WGS84

If you are using new Cassini then the conversion will be
Cassini -> GDM200 -> WGS84

Just not to confuse you currently Malaysian coordinate systems are using GDM2000 as our datum. Previously was Kertau48.

Noordin

13
Newbie's GIS / Re: Topic For GIS Thesis
« on: December 24, 2009, 08:29:54 PM »
what r u doing? Master, PhD? What area? Huhhhh too many incomplete info for us to suggest.

14
Available Jobs / Vacancy for Software developer and Telematic engineer
« on: August 16, 2009, 10:31:57 PM »
Requirement:
A. Telematic Exec/Engineer
1. Experienced in handling road network data in GIS
2. Has some knowledge of AVLS
3. Good personality and PR.
4. Able to work in team
5. Preferably Diploma/degree in GIS/Electronic/Geomatic/ IT/electrical

B.Software development Exec/Manager
1. Experience in software development for at least 3 years
2. Has some knowledge of GIS/mapping
3. Good personality and PR.
4. Able to work in team
5. Preferably degree in Computer Science/IT/GIS

Office is in Kuala Lumpur area. Please send resume with expected salary to noordin_ahmad@gmail.com

Only short listed candidate will be notified for interview.

15
Available Jobs / GIS ICT manager
« on: February 05, 2009, 12:01:17 AM »
There is an opening for those who have experience in handling GIS with ICT integration mainly databases (oracle/Sql server etc) and web services. Knowledge of hardware will be an added advantage. We are looking at those with at least 3 years experience so fresh graduate will not be considered. Please send your CV to noordin.ahmad@gmail.com stating your work experience and expected salary.

NA


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