Friday, August 15, 2014

Peta kontur 3d untuk pendaki gunung

untuk semua pendaki gunung baik yang pro maupun newbie, kali ini saya menyajikan peta 3d beberapa gunung di indonesia sudah ada di dalamnya waypoint dan track log nya, barang kali bisa dijadikan bekal adventure mountainers semua, tapi sebelumnya, kita bahas urusan garis kontur dulu, barang kali ada yang belom paham.
Sifat-sifat garis kontur
1. Garis kontur dengan ketinggian yang lebih rendah mengelilingi garis kontur yang lebih tinggi, kecuali bila disebut secara khusus untuk hal-hal tertentu seperti kawah.
2. Garis kontur tidak akan pernah berpotongan
3. Beda ketinggian antara dua garis kontur adalah tetap, walaupun kerapatan dua garis kontur tersebut berubah-ubah.
4. Daerah datar mempunyai kontur yang jarang-jarang, sedangkan daerah terjal atau curam mempunyai garis kontur yang rapat.
5. Garis kontur tidak akan pernah bercabang.
6. Punggung gunung atau bukit terlihat di peta sebagai rangkaian garis kontur yang berbentuk huruf “U” yang ujung melengkungnya menjauhi puncak.
7. Lembah terlihat di peta sebagai rangkaian garis kontur yang berbentuk huruf “V” yang ujungnya tajam dan menjorok ke arah puncak.
8. Garis kontur berbentuk kurva tertutup.
9. Garis ketinggian pembantu, menyatakan ketinggian antara (tengah-tengah) antara dua garis yang berurutan

Nah, setelah mengetahui sifat-sifatnya, secara umum membaca garis kontur di peta adalah sebagai berikut :
1. Di peta yang ane bikin, garis kontur yang tebal menandakan kontur kelipatan 100. Jadi antara garis kontur yang tebal dengan garis kontur tebal lainnya memiliki beda ketinggian 100 meter. 
Contoh : Garis kontur tebal pertama menunjukkan ketinggian 1200 mdpl. garis kontur tebal setelahnya pasti 1100/1300 mdpl tergantung medan.

2. Garis kontur tipis yang ada di peta menunjukkan perbedaan ketinggian 20 meter. Jadi di antara 2 garis kontur tebal pasti ada 4 garis kontur tipis.
Contoh : Di antara 2 garis kontur tebal yang masing-masing memiliki ketinggian 1100 mdpl dan 1200 mdpl pasti terselip 4 garis kontur tipis, dengan masing-masing ketinggian 1120, 1140, 1160, 1180 mdpl.

3. Makin rapat garis kontur, artinya makin terjal/curam medannya. sedangkan makin renggang garis kontur artinya makin landai medannya.

4. Perhatikan koordinat yang ada di sisi peta (atas bawah kiri kanan) di situ ada koordinat kan? di bagian atas dan kiri itu koordinat geografis, sedangkan koordinat di kanan dan bawah itu koordinat UTM. koordinat itu menunjukkan lokasi absolut dari suatu lokasi. Semisalnya agan nyasar, tapi sukur bawa GPS. Plotin titik koordinat agan, kemudian cari di peta supaya agan ngerti berada di mana. Setelah itu plotin titik-titik pos yang tertera di peta sebagai patokan agan untuk kembali ke jalur yang benar

oke paham?
mari sedot bersama sama

Peta Kontur 3D Gunung Rinjani
http://indomapimages.blogspot.com/ peta rinjani

Peta Kontur 3D Gunung Semeru
http://indomapimages.blogspot.com/ peta semeru

Peta Kontur 3D Gunung Merbabu
http://indomapimages.blogspot.com/ peta merbabu
Peta Kontur 3D Gunung Merapi
peta merapi

Klik kanan Imagenya
Lalu View Image in the new tab

kalo mau download ukuran A3
silahkan klik link berikut


BIG THANKS TO FIKRI FAUZI FIRDAUS ATAS KARYANYA


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Thursday, August 7, 2014

which datum transformation should you use?

You know when you're using a tool, or adding a data layer into ArcMap, and you get that Geographic Transformation option window? Most likely, you just use the default and click on through whatever you're doing. But if you want to learn more about which datum transformation is actually the best to suit your purpose, ESRI provides some great information in their online help.

When originally defined, North American Datum 1983 (NAD 1983) and World Geodetic System 1984 (WGS 1984) were equivalent. In order to minimize coordinate changes, NAD 1983 is tied to the North American and Pacific (for Hawai'i, etc.) plates. WGS 1984 is tied to the International Terrestrial Reference System (ITRF), which is independent of the tectonic plates. Over time, the two coordinate systems are increasingly different. 

Instructions provided help in determining the correct datum transformation to use when transforming data between the NAD 1983 and the WGS 1984 datums.

Procedure
NAD_1983_To_WGS_1984_1 
Published accuracy from EPSG is 2 meters. This transformation applies to the entire North American continent. Accuracy of the transformation varies, with greater accuracy at southern latitudes, and less accuracy at more northern latitudes with maximum offset of 2 meters. 

This transformation uses the Geocentric Translation method, with the transformation's parameters (dx, dy, and dz) all equal to zeroes. This transformation treats the NAD 1983 and WGS 1984 datums as though they are equivalent. 

NAD_1983_To_WGS_1984_2 
Calculated by the U. S. Defence Mapping Agency (DMA), now known as the National Geospatial Intelligence Agency (NGA) for the Aleutian islands. Accuracy is listed by EPSG at +/-8 m. 

NAD_1983_To_WGS_1984_3 
Calculated by the NGA for Hawai'i. Accuracy is listed by EPSG at +/-4 m. 


NAD_1983_To_WGS_1984_4 
Formerly applied within the 48 contiguous states, but is superseded by _5. This transformation method should no longer be used. 

NAD_1983_To_WGS_1984_5 
Transformation parameters calculated by the U. S. National Geodetic Survey (NGS) using CORS stations, and ties WGS 1984 to ITRF96. Accuracy according to EPSG is +/- 1 meter. 

NAD_1983_To_WGS_1984_6, _7, and _8 
Canadian NTv2 transformations, for the Quebec, Saskatchewan and Alberta provinces, respectively.
Each of these datum transformations can be used for the specified area, and arguments can be made for the application of each transformation. One of the most important considerations is consistency, using the same transformation each time, to transform between these two Geographic Coordinate Systems (datums). When using the Project Tool, the transformation method is recorded in the metadata.
The European Petroleum Survey Group (EPSG) database can be downloaded at the similarly titled link in Related Information. This database is a free download, and is updated frequently. This database includes information on the source of datum transformation parameters, and in many cases includes the accuracy of the transformation from the transformation source.
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Using Python to Fix Broken Links

If you’ve ever had a map document with a bunch of red exclamation marks on it, you know how frustrating it can be to go in an manually repair the data source for every single layer. Now, thanks to the ArcPy module in ArcGIS 10, you can write a small Python script that will help to speed this process.

Read the entire article to see how!


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Creating PDF Files with Geospatial Location and Attributes

ArcMap layouts can be exported to .pdf files that contain both the lat/long coordinates (geospatial location) of the data and the attributes of the map layers. For example, you can export a map that shows the location of rivers and rain gages around Houston, and the river names, along with whatever other attributes you have about the rivers (flood stage, sediment loads, etc.) can be included (and viewed) in the .pdf as well as the lat/long of each rain gauge. To include the lat/long values and the layer attributes in a .pdf, simply create a layout in ArcMap and export it as a .pdf file, using a few special settings in the .pdf export dialog. Click here to read the entire article.
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Random Number Generator for the Field Calculator

Have you ever wanted to add a field of random numbers to an attribute table? Using a little bit of Python scripting and the Show Codeblock function in the Field Calculator, you can easily achieve this.

We've created a calculation file that you can load into the Field Calculator and tweak to your liking. 
  • Download our random_number.cal file (right-click and choose Save As).
  • Open the Field Calculator for the attribute field you want to populate with random numbers.
  • Select the Python parser at the top of the window.
  • Click the Load button and select the random_number.cal file.
  • Once it's loaded, modify the numbers in the bottom portion of the window to suit your minimum and maximum value preferences.
  • Click OK and let it work 

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Tuesday, April 15, 2014

Creating regions in ArcMap after polygons are built

Use this procedure to make a multipart polygon from independent polygons that are already digitized.

1) Open the Editor toolbar and start editing.  (If the Start Editing window appears,
choose the directory source which contains the shapefile to be edited.  The desired
shapefile must be resident within the TOC.)

2) Within the Editor toolbar choose the shapefile to be edited within the Target window.

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Monday, April 14, 2014

Polygon-Raster Overlay

A procedure for generating a raster whose cell values reflect the sum of
the area of polygons in a shapefile that fall within each raster cell

Input for this description is a single shapefile of land use identified
as "la93_org.shp"

Assume: 
- the data frame, and operations, will be in UTM, Zone 11 projection
- the output raster cells will be 5km x 5km
- the extent of the raster is:
     top: 3726519.06
     left: 423994.79
     bottom: 3711519.06
     right: 438994.79
- the raster, based on cell size and exent, will have 3 x 3 cells  
   (this is small intentionally for demo purposes)
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