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How to Search for MODIS Products by TileID on the EDG

This tutorial gives step-by-step instructions for searching by tile(s) on the EOS Data Gateway (EDG). It is not a comprehensive tutorial on EDG functionality. Help with using the EDG is available from every EDG page throughout the search and order process. Please contact NSIDC User Services for additional questions regarding your order or MODIS data products.

Each MODIS product tile has a unique Tile Identification Number (TileID) based on the product, projection, tile size, and position. Thus, to order MODIS Land Products by specific tile, you must know the TileID for the specific tile you are searching for. TileIDs are not part of the file naming convention so this tutorial provides information on how to determine TileIDs.

The first section of this tutorial explains how to read and understand the TileIDs, the second section of this tutorial gives step-by-step search instructions, and the third section of this tutorial describes how to view search results and order the granule(s).

Section I: Understanding MODIS Land Product TileIDs
Section II: Searching for MODIS Products by Tile
Section III: Viewing Results and Ordering Granule(s)

Section I: Understanding MODIS Land Product TileIDs

Each MODIS product tile has a unique TileID based on the product, projection, tile size, and position. This TileID consists of an eight-digit integer, for example the TileID for the 6 grid cell over and the 14 grid cell down for MOD10A1 is 51006014.

The naming convention for this eight-digit integer, pshhhvvv, is described below:

• p = projection
  Possible values:
  • 1-Intergized Sinusoidal projection
  • 2-Goode’s Homolosine projection
  • 3-Lambert Equal-Area (EASE) Grid Projection center at the North Pole
  • 4-Lambert Equal-Area (EASE) Grid Projection center at the South Pole
  • 5-Sinusoidal projection
• s = tile size
  Possible values:
  • 1-full size
  • 2-quarter tile size                     
  • 4-one-sixteenth tile size
• hhh = projection dependant horizontal tile number.
• vvv = projection dependant vertical tile number.

Note: Not all MODIS Land Products can be searched by tile. The following are snow and sea ice products that can be searched by tile with their respective projection number and tile size specified.

Section II: Searching for MODIS Products by Tile

The images in this tutorial show only the portions of the window that are relevant to the step being described. If a table (such as a data set list) is very wide or long, only certain rows and/or columns may be shown. Green arrows or boxes on the figures shown in this tutorial indicate actions and selections.

1. Enter the EDG from the Main EDG Web page.
1. The Earth Observing System Data Gateway Main Web page displays. Refer to Figure 1.

2. From the Main EDG Web page, click on one of the following choices:
   1. Click on Enter as guest if not a registered user.
   2. Click on Enter as a registered user if a registered user.

Figure 1: Earth Observing System Data Gateway Main Web Page

Primary Data Search

In this section, you will choose the MODIS data set you want by completing the following steps.

1. Click on the By Categories/Attributes option button. Refer to Figure 2.

Figure 2: Primary Data Search Window

In the following steps, you will select keywords for the data set.

2. Under the Choose Keywords for One or More Categories field, click on DATA SET in the category list. Refer to Figure 3.


3. Click on the Choose Keywords for>> button.

Figure 3: Choose Keywords for One or More Categories

4. Scroll through the various lists until you find the data set you want to order. Refer to Figure 4.


5. Click on the data set to select it.


6. Click on the OK! button.

Figure 4: Keyword Selection: Data Set Window

Spatial Sub setting

In this section, you will specify the tiles you want by completing the following steps.

1. Under the Choose Keywords for One or More Categories field, click on Spatial in the category list. Refer to Figure 5.


2. Click on the Choose Keywords for>> button.

Figure 5: Choose Keywords for One or More Categories Window.

The following Web pages will help you use projection, tile map(s) and TileID naming conventions specific to your data set to determine the tiles you want in the following steps:

• MODIS Sinusoidal Grid 
• Lambert Equal-Area (EASE) Grid Projection

3. Choose one of the following steps for ordering by tile:
   1. If you want a single tile, enter the TileID in the TileID box. For example, 51018002. Refer to Figure 6.
   
   
   2. If you want a range of tiles, enter the Horizontal Tile Number range, for example 2 to 4, and the Vertical Tile Number range, for example 12 to 16, in the respective boxes. Note: Step B only works for all snow products and the northern hemisphere sea ice products. The southern hemisphere sea ice products do not work because the interface rejects values greater than 18.

4. Click on the OK! button.

Figure 6: Select: SPATIAL Window

Now that you have specified your data set and the tile(s), you will now specify your search type.

5. Under the Choose a Data Search Type field, click on the Primary Data Search option button. Refer to Figure 7.

Figure 7: Search Creation: Primary Data Search Window Displaying Only Two Fields

The following step is optional, and you only need to do it if you want to choose a time period.

6. Under the Choose a Data/Time Range field, enter a time period. Refer to Figure 8.

The following steps are optional, and you only need to do them if you want to verify that the appropriate tiles were returned. You can add the tile information to the metadata displayed as a result of your search by performing the following steps:

7. Under the Choose Additional Options field, click on the Customize option button. Refer to Figure 8.

Figure 8: The Choose a Data/Time Range and Choose Additional Options Fields.

8. Under the Available Metadata list, click on TILEID. Refer to Figure 9.


9. Click on the Add button.


10. Click on the OK, Accept Selections button.

Figure 9: The Customize Metadata Search Results Window.

11. On the Search Creation: Primary Data Search window, scroll down to the bottom of the window, and click on the Start Search button. Refer to Figure 10.

Figure 10: The Search Creation: Primary Data Search Window.

The Search Status: Search in progress… window displays, refer to Figure 11, until the search is complete. Once the search is complete, the Results: Granule: Listing window displays. Refer to Figure 12.

Figure 11: Search Status: Search in progress… Window.

Section III: Viewing Results and Ordering Granule(s)

Viewing Results

The following are optional steps to help you determine which granules you want to order. A quick way of checking to see if the correct granules were returned for your chosen tile or range of tiles is to click on either the Attributes link or the Metadata link of a granule, and look to see if the field TileID is present and contains a value consistent with the query you made.

If you click on the Attributes link, you will receive an html format file, If you click on the Metadata link, you will receive a code format file.

To check the spatial location of a granule, you can click on the Image Quick Look link. Another way to check the spatial location of a granule(s) is to select a few granules and click Show Map Coverage

In the following steps, you will verify if the field TileID or Horizontal TileID and Vertical TileID is present:

1. Depending on the type of format you want to receive, choose one of the following steps:
   1. Click on the Metadata link to receive a data file format. Refer to Figure 12.
   2. Click on the Attributes link to receive an html file format.
   
   
2. Select a few granules and click on the Show Map Coverage option button.
1. A spatial map displays above the granule with the coverage of the granule highlighted. Refer to Figure 13.

Figure 12: Results: Granule: Listing Window.

Use the rotate map and zoom tools to get a closer look at the coverage area.

3. From the map, verify that the spatial location is correct. Refer to Figure 13.

Figure 13: Spatial Map

Ordering Granule(s)

In this section, you will order the granule(s) you want.

1. Select the granules that you want to order by clicking the box next to the granule ID. Refer to Figure 14.


2. Click the Add Selections to Cart option button.
1. As the shopping cart process begins, a Shopping Cart: Data Quality Summary report displays. Refer to Figure 15.

Figure 14: Spatial Map

At this point, you are done searching by tile(s) on the EDG. The system will prompt you through several more steps to complete the ordering process. If you have any questions while completing the ordering process, please see the Ordering MODIS Snow and Ice Products Using the EOS Data Gateway tutorial.

For more information about MODIS snow and sea ice data products available at NSIDC, please see the MODIS Data at NSIDC Web page, or contact NSIDC User Services.

Figure 15: Shopping Cart: Data Quality Summary Window.

Page last updated: 08/27/07