Archive for September, 2007

Avenue – Dialog Designer – Menu Dropdown List

September 20th, 2007

dropdown

Saudara Mario kembali bertanya tentang avenue-dialog designer (Lihat posting sebelumnya http://inigis.info/blog/avenue-dialog-designer/).
Kurang lebih pertanyaannya adalah sebagai berikut :

Pada dialog designer diatas, bagaimana mengisi otomatis dropdown menu sesuai dengan databasenya (atributnya)?

Perlu dipahami bahwa untuk memunculkan unique value dari fieldnya, maka yang pertama script Anda harus mengaktifkan field tersebut terlebih dahulu. Baru kemudian membuat list unique value dari field tersebut. Dalam kasus saudara Mario, berarti akan ada 2 field yang akan diaktifkan. Selengkapnya script untuk jawaban pertanyaan diatas adalah sebagai berikut : » Read more: Avenue – Dialog Designer – Menu Dropdown List

ArcMap: Creating New Shapefiles from MS Excel Spreadsheets

September 5th, 2007

arccatalog

These instructions address how to convert a tabular list of point coordinates into a new ESRI shapefile. The users can also use them to save data to a geodatabase feature class.

  1. Open ArcMap.
  2. Create a new project and save it.
  3. Add background data to the data frame. Use the “Add Data” button or drag and drop from ArcCatalog.
  4. Start MS Excel. Open the file with the data and coordinate information. You can have fields in your table other than the Northing and Easting (or X & Y) fields. **If you are using geographic coordinates for the X & &, they need to be in decimal degrees. West and South coordinates need to have a negative sign in front. See note below on converting Degrees, minutes, seconds to decimal degrees.
  5. Clean up the file to delete fields of data you don’t need in the final shapefile.
  6. Make sure the Northing and Easting (or X & Y ) columns are formatted to numbers. If you do not have decimal places, specify that in the format dialog box. **If you are using geographic coordinates, it is best to have at least 5 digits after the decimal to make sure your data is precise enough for large scale mapping.
  7. Put the curser in the cell directly below the last lower right cell holding your data.
  8. Save your file to a format that ArcMap can read. File menu –> Save As. Try one of the following two formats: a. Dbase IV
    b. Comma Delimited. You will need to make sure the file extension actually reads txt. To do this, choose “comma delimited (csv)” as your Save As type. Then change the name of the file to include a .txt and put the whole filename in quotes.
  9. Close MS Excel.
  10. Return to the ArcMap project.
  11. Start the dialog box to add XY data. Tools menu –> Add XY Data
  12. This tool allows you to show the location of XY coordinates from a file on-the-fly. Fill in the following sections of the dialog box and then click OK. Name (navigate to the file using the folder button on the right) choose the correct X and Y field headings from you table. Set the Spatial Reference (click on the “Edit” button). You need to do this so the program know what projection and datum the coordinates are in.
  13. The data will display in the data frame map area. Check to make sure all of the positions are present and that there is no error in the attributes or relative locations.
  14. 14. Save the data to a shapefile. Right click on the filename in the TOC –> Data –> Export Data –> shapefile. Be sure to read the Export Data dialog box carefully for information on the coordinate system to assign to the data.

DMS –> dd: D + M/60 + S/3600 = dd
Example: 45°30’45.22”: 45 + 30/60 + 45.22/3600 = 45.512561

ArcGIS – Tables

September 5th, 2007

Whether it is a .dbf from a Shapefile or a PC ArcInfo Coverage, an info file from an ArcInfo coverage, or a MS Access table, creating and editing tables is an intricate part of the day to day tasks in GIS.

 

arcgis_tables

 

 

Tables can be manipulated in ArcMap, ArcCatalog, and through the ArcToolbox in ArcGIS. How the tables are accessed and edited will depend on the needs of the task to be accomplished and the preferences of the technician.

Here are a few tips that will make working with tables in ArcGIS a little easier:

* Some characters in field or table names are not supported.

o Names must not have a space.

o Names must not have a hyphen. (Example x-coord)

o Names must not have brackets.

o Names must not have special characters. (# * / ~)

o Names must not start with a number or underscore.

* Field names in delimited text files must be edited to remove these unsupported characters before using them.

* Tables that contain Memo fields cannot be accessed in ArcGIS.

* Field and table names can be 31 characters for Geodatabase feature classes.

* A dBASE field name can be up to 10 characters long.

* A dBASE table name has no limit to the length.

* Up to 16 letters or numbers can be used in coverage field and table names.

ArcGIS – Transparency Vector & Raster

September 5th, 2007

In ArcView 3.x, there was a transparent symbol in the Symbol Palette. In ArcGIS 9.x, a user needs to load a special toolbar to symbolize features as transparent. In addition, a user can change the brightness of an image using this same toolbar.

 

arcgis_transparency

Go to View > Toolbars > Efects to load the Effects Toolbar

* Choose Lakes under Layer

* Click the Transparency button and move the slider bar to 50% You will see the municipal boundary through the lakes now

* Check on the MrSID in your TOC

* Choose MrSID under Layer in the Effects Toolbar

* Click on the Brightness button and adjust up and down. You will see the image change