Research Note #22 - Reading GCOM-C 250m-Res HDF5 Data with Fortran

There were not so many references about 'simple' ways to open and read HDF5 data file with Fortran as well as compiling the codes. I said 'simple', because there are actually manuals and tutorials about that purpose, however, most of them were too complicated and refer to other sub-references, thus blah .. blah ... it takes too much time, especially if you just simply want to open, read and compile a HDF dataset. Here, I posted a very basic way to access HDF5 data, using very minimal Fortran code. Before starting, here's the convention:

• I used Linux OS. 
• I used Fortran 90 for programming.
• HDF5 (ver 1.8.17) libraries has been already installed in my system as module.
• I used JAXA's GCOM-C NDVI Monthly statistics (Level-2 data) with 250m spatial resolution with Sinusoidal/EQA projection. This data contains 4800x4800 pixels. For exemplary purpose, I renamed it to "ndvi.h5".

So, the following is a very basic example of Fortran code to open and read HDF5 data:

PROGRAM HDF5test

   USE HDF5

   IMPLICIT NONE

   INTEGER :: hdferr, i, j

   INTEGER(HID_T) :: fileid, dset

   CHARACTER(LEN=7), PARAMETER :: filename = "ndvi.h5"

   CHARACTER(LEN=19), PARAMETER :: dataset = "Image_data/NDVI_AVE"

   INTEGER, PARAMETER :: xdim = 4800

   INTEGER, PARAMETER :: ydim = 4800

   INTEGER, DIMENSION(1:xdim, 1:ydim) :: ndvi_ave

   INTEGER(HSIZE_T), DIMENSION(1:2) :: dims = (/xdim, ydim/)

   

   CALL h5open_f(hdferr)

   CALL h5fopen_f(filename, H5F_ACC_RDONLY_F, fileid, hdferr)

   CALL h5dopen_f(fileid, dataset, dset, hdferr)

   CALL h5dread_f(dset, H5T_NATIVE_INTEGER, ndvi_ave, dims, hdferr)

    DO j = 1, ydim

      DO i = 1, xdim

         print *, ndvi_ave(i,j)

      ENDDO

   ENDDO

  CALL h5dclose_f(dset, hdferr)

  CALL h5fclose_f(fileid, hdferr)

  CALL h5close_f(hdferr)

END PROGRAM HDFtest

The most important lines are:

• CALL h5open_f(hdferr). This function initializes HDF5 library for Fortran uses. Returns 0 (to hdferr variable) if it's successful, and -1 if it's failed.
• CALL h5fopen_f(filename, H5F_ACC_RDONLY_F, fileid, hdferr). This function opens an existing HDF5 file. In this example, I just want to read it, hence H5F_ACC_RDONLY_F was used as argument. This function will return integers for file identifier and status to fileid and hdferr variables, respectively.
• CALL h5dopen_f(fileid, dataset, dset, hdferr). This function opens an existing dataset in the opened file. Take notice that it needs file identifier (from h5fopen_f), dataset name, dataset identifier and status (as previous functions).
• CALL h5dread_f(dset, H5T_NATIVE_INTEGER, ndvi_ave, dims, hdferr). This function reads raw data from dataset of the file, into a buffer. The buffer means a space in the computer memory, this could be a variable or array. Take notice that it need dataset identifier (from h5dopen_f), memory data type (Native integer), buffer, dimension (to store buffer dimension) and as always, status (hdferr).

To make it simple, the program will firstly initialize HDF5 library, opens an existing HDF5 datafile, opens a dataset from that file (a file could consist of many datasets), read the raw data from the dataset, put the data into an array buffer, then prints the contents of the buffer into the screen. Finally, it closes the dataset, closes the file and ultimately deactivates HDF5 library (flush and cleans the memory). That's all.

Another important thing is variable declaration. HID_T and HSIZE_T are parameters for predefined datatype used by HDF5 library. So, don't be confused with them (for details, just read: https://support.hdfgroup.org/HDF5/doc/fortran/index.html).

Finally, save and give the codes a name (for example: test.f90). To compile the code, just use this command on (bash) shell:

$ h5fc -o test.exe test.f90

It's just similar with a normal Fortran compiler command. If you don't specify a name for the output, a file named 'a.out' will be generated by the compiler.

Gunpla #50 - HGUC Gundam TR-1 [Hazel-Rah] Review

I was so busy with my study for the last one month, thus in order to save time, I decided to make a review of a combination of two HGUC kits instead of reviewing them individually (I will do it soon though). This time, the lucky kit is Gundam TR-1 [Hazel-Rah], or just call it Hazel-Rah. 

I'm pretty sure, many of you, in particular the AoZ fans, knew what it is. Hazel-Rah is actually not an official kit, but rather a combination between HGUC Gundam TR-1 Hazel Custom and HGUC Hrududu support fighter, which makes it officially an upgrade of HGUC Hazel-custom. These two kits were actually released by Bandai in the past: Hazel custom as retail released in 2005, followed by Hrududu as an add-on of Dengeki Hobby magazine in 2006. Since Bandai recently got license to AoZ designs, they started releasing many AoZ kits in the past one year. Hazel custom and Hrududu eventually received a re-make, and finally released as p-bandai last month. I won't talk much about each kit, but rather reviewing the end product of their combination.

So, Hazel-Rah is basically a Hazel custom equipped with Hrududu as its backpack, and got an extension for its beam rifle. It is quite similar with HG 00 Gundam combined with 0 Raiser (which was also reviewed in this blog). For making Hazel-Rah, you need a retail or p-bandai Hazel Custom and a p-bandai Hrududu. Yes, a retail OR p-bandai Hazel Custom. I said this because the manual actually states that it needs an unassembled p-bandai Hazel Custom while it actually could use a retail one as well, assembled or unassembled. Greedy Bandai!

If you have already constructed Hazel Custom, you could simply just remove the red cockpit piece from the kit and put the cockpit part of Hrududu on the chest section of Hazel Custom, then put the main body and wing section of Hrududu on Hazel Custom's backpack. Finally, just add the blade rifle sections to the Hazel Custom's beam rifle, and that's it.

While Hazel-Rah could actually stand on its own, I suggest you to use an action base because of the heavy backpack. Another issue is articulation. With such heavy add-ons, moving the body parts is becoming difficult, thus don't expect much for dynamic poses with this kit. If you have two Hrududu kits, you actually could make a second-form variant of Hazel-Rah. Furthermore, if you could kitbash it with Advanced Hazel's scope, subarms and feet to make Hazel-Rah Full Armor form. As a gimmick, the 'claw' on Hrududu's right wing could open, and you could put blade rifle or beam saber effect (I suppose) on it.

As verdict, Hazel-Rah is a great kit. If you have already had a Hrududu, you MUST combine it with Hazel Custom. While this giant lacks articulation because of its massive body, the presentation itself is really amazing. Just put it on your work desk, and you could feel really badass for whole day, believe me (lol). Finally, remember, aside from Hrududu (which is a p-bandai), you only need retail a Hazel custom to make it, not a p-bandai one. 

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RX-121-1+FF-X29A Gundam TR-1 [Hazel-Rah]

Pros:

• Beautiful (and badass) aesthetics

Cons:

• Limited articulation