dem from ifsar

[Norasyikin Mehat]

can anybody help me with generating dem from ifsar? my ifsar came with dsm and dtm. i dont even know where to start T.T

[Adam Atia]

Hey Norasyikin,

I have dealt with DEM (digitial elevation model) data before but not dsm or dtm, I found this link to a forum post that discusses this:

http://gis.stackexchange.com/questions/5701/what-is-the-difference-between-dem-dsm-and-dtm

However, have you been able to plot the dsm or dtm data? Perhaps if you attach an example data file, I can try to look into it further using MATLAB. So attach a data file and I can give it a shot! 

What is your objective for using these data? It would be more helpful if I had an overall idea of what your project is.

Adam A

[Norasyikin Mehat]

Hi Adam, fyi im doing a research about flood hazard. So I need DEM for my terrain and flood simulation analysis. I tried to process them using Arcgis, by using 3d analyst tool, reclassify and generate contour but I think its not right. Ive been asking people around and some people told me that I must pre process them in a RS software first.

I found a tutorial on utube that use global mapper so I installed the software and when I tried to load ifsar, gm wont read .img, a fren told me I have to convert .img to .mat if I want to use gm

And unfortunately, I can't share the data because its restricted. Im sorry T.T

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[Adam Atia]

Hi,

It makes it hard to figure out a solution if I don't know much about the data that you have. I am guessing that you didn't download the data from some source since it is restricted. There should be some metadata for your data though that might help you figure out how to deal with your situation. I'd say look at the metadata.

You said that you loaded a .img file. Can I ask if there are other file extensions that came with your data? 

Aldo, do you have access to matlab? Last questions: (1) What is the resolution of of your data (e.g. 30 meters) and (2) Can you use a different source of DEM data instead of your ifsar data?

AAA

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[Adam Atia]

Most of all, all of the exact file extensions that you have would be helpful to know (e.g., .tiff, .nc, or others).

On Tuesday, November 4, 2014 2:27:43 AM UTC-5, Norasyikin Mehat wrote:

[Norasyikin Mehat]

Yes theres file extensions .aux and.rrd, im not sure if i already uninstalled matlab from my desktop..my data resolution is 5m and yes i can get contour lines to generate dem or any other sat image but my prof prefer ifsar bcause it produces high resolution

So what do u mean by go through the metadata? Assume that i know nothing about this whole metadata things. What should i do first?

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[Adam Atia]

Metadata are simply notes that describe everything about the data you are using. So whoever created the dataset would typically create metadata so that other users would know the details of the data they are using.

In your case, it seems the professor just gave you some data that he or she had. Let's forget about metadata for a second. You said you were able to project your data in GIS but that it didn't seem right. Can you tell me what was wrong? Why do you think it is incorrect? Perhaps all you had to do was load your data as you did and then play with the colorbar to clearly see distinct topographic features. So can you describe why you think what you did was wrong?

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[Adam Atia]

Also, you only mentioned .rrd and .aux. What is the extension of the file you tried to load? .tif? .img? Please clarify.

[Norasyikin Mehat]

Okay, if u dont mind i'll send email to u

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