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I have a shapefile (my basin limit) and one raster file that I projected it to the shapefile coordinate system and set its cell size to 1000m(area=1Km2). my basin area is 5400 Km2 and it should contain almost 5000 cell of raster file at least. but just one and a half cell put on this range. what's the problem? enter image description here enter image description here enter image description here enter image description here

  • Some pictures and a gdalinfo might shed a bit more light on the subject. – Michael Stimson Jun 21 '14 at 9:34
  • unfortunately I don't know how can I upload a picture with my question. may you tell me? – hadis Jun 21 '14 at 9:43
  • Go back to edit question and insert a picture by clicking on the picture button. First of all it must be a file, so use Alt + PrntScr (Print Screen button) to get a snapshot of the active window then paste into paint then crop to just the interesting area and mask any personal/private detail. – Michael Stimson Jun 21 '14 at 9:47
  • So what's the properties of the raster before and after projection? – Michael Stimson Jun 21 '14 at 9:54
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    Don't set the cell size, use resample resources.arcgis.com/en/help/main/10.2/index.html#//… after projection. 1 degree east-west is 111.32 kilometres so half of that is 55.66 km at the equator and considerably less than that as you move further away. en.wikipedia.org/wiki/Decimal_degrees – Michael Stimson Jun 21 '14 at 14:29
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As Michael is stating you have gone wrong in the process.

Use the MODIS reprojection tool to output the date in the projection you desire. https://lpdaac.usgs.gov/tools/modis_reprojection_tool

It this statement that is the problem. "it is a modis ET product (MOD 16) and didn't have any coordinate system. my basin projection is Lambert Conformal Conic or UTM-WGS 1984- zone 38N.(both of them is acceptable for my work). so i changed its projection to both of these projection systems but this problem didn't solve. – hadis 9 hours ago"

You cannot just "change" the Projection like this.

Use the tool I showed you and you can set the data to your UTM zone as output.

Then use resample to set the cell size as Michael is saying but the tool does this as well.

You can do it all in ArcGIS but you need to understand the difference between setting a projection and reprojecting. The tool is the way to go.

You should also 100% verify it is the raster that is incorrect (I think it is but am not certain). Sn easy way to do this is bring a base layer in from arcgis (say world imagery) into a fresh MXD then after this add your vector boundaries then after this add your raster and this will confirm which of the two is the problem. Here is the link to the imagery

arcgis.com/home/item.html?id=a5fef63517cd4a099b437e55713d3d54

then get back to us and tell us if it is the raster or vector that is incorrect. I suspect it is the MOD16 and it is an incorrect projection work flow that the tool above fill help resolve.

  • Another thing you can do is bring a base layer in from arcgis (say world imagery) into a fresh MXD then after this add your vector boundaries then after this add your raster and this will confirm which of the two is the problem. Here is the link to the imagery arcgis.com/home/item.html?id=a5fef63517cd4a099b437e55713d3d54 then get back to us and tell us if it is the raster or vector that is incorrect. I suspect it is the MOD16 and it is an incorrect projection work flow. – If you do not know- just GIS Jun 21 '14 at 21:06
  • It is a very common beginner mistake @user, so much so that in the meta it came up as a topic on canonical questions. +1 for summing up the comments into an answer; I was going to paraphrase this morning but would have included the following comment in the answer and not as a comment. It is (IMHO) very important to benchmark your data when something goes unexpected.. You can't say the raster is bad because it disagrees with the boundary unless you prove the boundary is correct (within tolerance) first! – Michael Stimson Jun 22 '14 at 0:51
  • Spot on MMS. I like the arcgis online maps for doing this or even Google Earth. – If you do not know- just GIS Jun 22 '14 at 1:47
  • as I said in a comment before, I downloaded some Geotiff Modis ET products , they are Georeference and their coordinate system are WGS-1984, so I don't need to change the projection, I had opened both of the raster and vector in google earth before and they were correct. also, I opened the raster by ENVI software and checked the coordinates and cell size, everything were OK. If you give me an email address I can send you the basin boundary and one of the rasters, so you can check them and tell me what's wrong. – hadis Jun 22 '14 at 9:16
  • post them somewhere and Ill take a look. Google drive gives you enough free online storage. – If you do not know- just GIS Jun 22 '14 at 13:14

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