[GRASSLIST:9087] Re: GRASS 6 in a nutshell tutorial

lponti at infinito.it lponti at infinito.it
Tue Nov 15 18:03:56 EST 2005


Dear Ian,

the original metadata of my state outline shapefile is:

PROJCS["unnamed",GEOGCS["NAD83",DATUM["North_American_Datum_1983",SPHEROID["GRS 
1980",6378137,298.257222101,AUTHORITY["EPSG",7019]],TOWGS84[0,0,0,0,0,0,0],AUTHORITY["EPSG",6269]],PRIMEM["Greenwich",0,AUTHORITY["EPSG",8901]],UNIT["degree",0.0174532925199433,AUTHORITY["EPSG",9108]],AXIS["Lat","NORTH"],AXIS["Long","EAST"],AUTHORITY["EPSG",4269]],PROJECTION["Albers"],PARAMETER["standard_parallel_1",34],PARAMETER["standard_parallel_2",40.5],PARAMETER["latitude_of_center",0],PARAMETER["Central_Meridian",-120],PARAMETER["False_Easting",0],PARAMETER["False_Northing",-4000000],UNIT["m",1]]

Based on this, following direction in the GRASS/cygwin 
installation page
http://geni.ath.cx/grass.html#toc15

I have created a dummy vector for reprojection of the 
raster DEM of western USA - e10g tile. Then I created a 
new location from EPSG code to match the vector .shp state 
outline file, and I have imported both the dummy raster 
DEM via "v.proj" and the vector state outline via 
"v.in.ogr".

Using "gdalinfo" on the original raster file (e10g), 
originated the following output:

gdalinfo c:/cygwin/home/andy/DEM_data/e10g
Driver: EHdr/ESRI .hdr Labelled
Size is 10800, 6000
Coordinate System is `'
Origin = (-180.000000,50.000000)
Pixel Size = (0.00833333,-0.00833333)
Corner Coordinates:
Upper Left  (-180.0000000,  50.0000000)
Lower Left  (-180.0000000,   0.0000000)
Upper Right ( -90.0000000,  50.0000000)
Lower Right ( -90.0000000,   0.0000000)
Center      (-135.0000000,  25.0000000)
Band 1 Block=10800x1 Type=Int16, ColorInterp=Undefined
   NoData Value=-500

Do you see anything wrong?

In addition, I tried to import v.in.e00 (after adding the 
required .exe file in the bin folder of GRASS) but I have 
not been successful yet.

Regards and thanks,

Luigi


On Mon, 14 Nov 2005 18:31:43 -0800
  Ian MacMillan <ian_macmillan at umail.ucsb.edu> wrote:
> Luigi, if you look at r.info and v.info, you will only 
>find the  projection information of your location, not 
>necessarily the  projection/datum/etc. information of the 
>original data (I believe).  Do  you have the original 
>metadata?  If not, try running gdalinfo on your  original 
>data files to determine their original projection info.
> 
> man gdalinfo
> will give you the correct syntax.
> 
> G'luck
> Ian
> 
> On Nov 14, 2005, at 2:06 PM, Luigi Ponti wrote:
> 
>> Thanks Amish,
>>
>> looking at v.info and r.info, it seems the two maps have 
>>the same  
>> projection (see below). However, when looking at the 
>>output "d.where  
>> -w" for a sample map point (the San Francisco Bay), the 
>>longitude is  
>> very different in the two maps:
>>
>>                                                   WGS84 
>>Co-ordinates
>>             EAST:             NORTH:               LON:
>>             -191114.6346037    -24240.66895625 
>> 143:03:58.588289W    
>> 29:24:27.1
>> (San Francisco Bay on the California State vector layer 
>>- WRONG)
>>
>>  1839139.30311877    663981.00484798  122:19:50.783112W 
>>  37:57:48.1
>> (San Francisco Bay on the Elevation Model raster layer - 
>>CORRECT)
>>
>> Do you think this could be due to an error in the import 
>>process or  
>> should I just look for another vector map?
>>
>> Thanks again,
>>
>> Luigi
>>
>>
>>
>> v.info map=state layer=1
>> +---------------------------------------------------------------------- 
>> ------+
>> | Layer:    state                          Organization: 
>>               
>>       |
>> | Mapset:   luigi                          Source Date: 
>>                
>>       |
>> | Location: Cal_nad83-zone3                Name of 
>>creator:             
>>       |
>> | Database: /home/andy 
>>                                                 
>>       |
>> | Title: 
>>                                                           
>>    
>>       |
>> | Map Scale:  1:1 
>>                                                      
>>       |
>> | Map format: native 
>>                                                   
>>       |
>> |---------------------------------------------------------------------- 
>> ------|
>> |   Type of Map:  Vector (level: 2) 
>>                                    
>>       |
>> | 
>>                                                           
>>           
>>       |
>> |   Number of points:       0               Number of 
>>areas:      51    
>>       |
>> |   Number of lines:        0               Number of 
>>islands:    48    
>>       |
>> |   Number of boundaries:   59              Number of 
>>faces:      0     
>>       |
>> |   Number of centroids:    51              Number of 
>>kernels:    0     
>>       |
>> | 
>>                                                           
>>           
>>       |
>> |   Map is 3D:              0 
>>                                          
>>       |
>> |   Number of dblinks:      1 
>>                                          
>>       |
>> | 
>>                                                           
>>           
>>       |
>> |   Projection: Lambert Conformal Conic (zone 0) 
>>                       
>>       |
>> |            N: 922206.900    S: -701781.905 
>>                           
>>       |
>> |            E: 1043412.917     W: -374425.808 
>>                         
>>       |
>> |            B: 0.000         T: 0.000 
>>                                 
>>       |
>> | 
>>                                                           
>>           
>>       |
>> |   Digitize threshold: 0.00000 
>>                                        
>>       |
>> |   Comments: 
>>                                                          
>>       |
>> | 
>>                                                           
>>           
>>       |
>> +---------------------------------------------------------------------- 
>> ------+
>>
>>
>> r.info map=e10g at PERMANENT
>> +---------------------------------------------------------------------- 
>> ------+
>> | Layer:    e10g                           Date: Tue Nov 
>> 8 17:25:24  
>> 2005    |
>> | Mapset:   PERMANENT                      Login of 
>>Creator: andy       
>>       |
>> | Location: Cal_nad83-zone3 
>>                                            
>>       |
>> | DataBase: /home/andy 
>>                                                 
>>       |
>> | Title:     ( e10g ) 
>>                                                  
>>       |
>> |---------------------------------------------------------------------- 
>> ------|
>> | 
>>                                                           
>>           
>>       |
>> |   Type of Map:  raster              Number of 
>>Categories: 5443        
>>       |
>> |   Data Type:    CELL 
>>                                                 
>>       |
>> |   Rows:         7192 
>>                                                 
>>       |
>> |   Columns:      11628 
>>                                                
>>       |
>> |   Total Cells:  83628576 
>>                                             
>>       |
>> |        Projection: Lambert Conformal Conic (zone 0) 
>>                  
>>       |
>> |            N:    3353466    S:   -3838238   Res: 
>>999.95884316         
>>       |
>> |            E:    6073284    W:   -5555183   Res: 
>>1000.04016168        
>>       |
>> |   Range of data:    min =  -84 max = 5443 
>>                            
>>       |
>> | 
>>                                                           
>>           
>>       |
>> |   Data Source: 
>>                                                       
>>       |
>> | 
>>                                                           
>>           
>>       |
>> | 
>>                                                           
>>           
>>       |
>> | 
>>                                                           
>>           
>>       |
>> |   Data Description: 
>>                                                  
>>       |
>> |    generated by r.proj 
>>                                               
>>       |
>> | 
>>                                                           
>>           
>>       |
>> | 
>>                                                           
>>           
>>       |
>> +---------------------------------------------------------------------- 
>> ------+
>>
>> Hamish wrote:
>>
>>>> I have imported both the vector and the raster with 
>>>>minimum trouble,  
>>>> since the first has a .prj file which GRASS recognized, 
>>>>and the  
>>>> second
>>>>
>>>> had a detailed import tutorial in the cygwin-GRASS 
>>>>install page.  
>>>> However, despite the fact the the two layers supposedly 
>>>>have the  
>>>> same NAD83 projection info (I did not enter anything 
>>>>manually), when  
>>>> I try
>>>> to  display them together on a GRASS monitor, the state 
>>>>layout is in
>>>> the  middle of the ocean compared to the elevation 
>>>>raster.
>>>>
>>>> Is there a way to overlap the two layers or to chek for 
>>>>a coordinate
>>>> error?
>>>>
>>>
>>>
>>> r.info and v.info will give you the map extents, you 
>>>should then be  
>>> able
>>> to figure out which is correct.
>>>
>>> Also try "d.where -w" to give you a lat/lon value for 
>>>different parts  
>>> of your map which you can compare to the map on the 
>>>wall.
>>>
>>>
>>> Hamish
>>>
>>>
>>>
>>
>>
> >
> >
> What happens if a big asteroid hits Earth? Judging from 
>realistic  simulations involving a sledge hammer and a 
>common laboratory frog, we  can assume it will be pretty 
>bad.
>  - Dave Barry
> 
> 
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