# Other common issues

## 1. Why is the imported HDRI blurry?

<mark style="background-color:purple;">High-definition HDRI takes up more resources when previewing, so the HDRI is compressed to 2k by the D5 when previewing to ensure that accurate lighting is provided.</mark>

* The image output is based on the actual size of the imported HDRI.&#x20;
* The HDRI is also compressed to 2K/4K/8K for video.

## 2. Why does it prompt " Failed to load HDRI"?

<mark style="background-color:purple;">Custom HDRIs imported into the D5 renderer need to be standard size files.</mark>

Common sizes:

| 1k       | 2k          | 4k          | 8k          |
| -------- | ----------- | ----------- | ----------- |
| 1024×512 | 2048 × 1024 | 4096 × 2048 | 8192 × 4096 |

> 1. Large HDRIs take longer to import and will take longer to render out.
> 2. Recommended HDRI download site: [Poly Haven](https://polyhaven.com/)

## 3. Why are there two angles of shadow in the scene?

In some HDRIs the sun is visible and already produces clear shadows. <mark style="background-color:purple;">If</mark> <mark style="background-color:purple;"></mark><mark style="background-color:purple;">**"Sun-Direction-Custom" is ticked**</mark><mark style="background-color:purple;">, it is possible to have this "heavy shadow" problem in certain cases, because there is already a sun in the original HDRI.</mark>

The following is recommended for adjusting the sky:

1. **Enable Follow HDRI.** Make the sun's altitude and azimuth auto-follow the sun in the HDRI. Adjust the angle of the sun by rotating the HDRI.
2. **Replace the HDRI with one that does not have the sunlight effect** (i.e. one that is more balanced in brightness). This will not produce more noticeable shadows, and this time use simulated parallel sunlight will allow you to make more controlled shadows.
3. **Use Geo and Sky.** Geo-Sky has fewer parameters controllable for the sun compared to HDRI, and is based on real geographic information to determine the sun's orientation and light changes.

## 4. How to adjust the Tyndall effect/volume light?

<mark style="background-color:purple;">In the second item of the "Environment" panel on the right sidebar, find</mark> <mark style="background-color:purple;"></mark><mark style="background-color:purple;">**"Weather" > select "Fog" > enable the "Volume Light" button**</mark><mark style="background-color:purple;">.</mark>

<div align="center"><figure><img src="https://3611830798-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F-MjbN1iGmN_HBnj_fyU9%2Fuploads%2F1tQaoOGXVJGzvH1VHkZS%2Fimage.png?alt=media&#x26;token=3ce24232-141a-4464-8cbf-a9e8fb591517" alt=""><figcaption></figcaption></figure></div>

* Volume Light: The Tyndall effect is a phenomenon in which light is scattered by particles in the air, allowing pathways of light to be seen.
* Scattering: Controls the scattering distribution of the Volume Light scattering effect. The default value is 0 for a uniformly light fog, adjusting it to 1 will make the fog brighter from the direction of the light source.

> Note: The issue of "preview is normal but output has no Tyndall effect" has been fixed in 2.9 version, please output with 2.9 version.

{% hint style="info" %}
**Note:**

If you get ‘stripes of light’ when creating the Tyndall effect/Volume Light, this is a known issue with the current 2.9 version. Please try giving the one-sided wall a certain thickness (or placing a plane outside the wall).
{% endhint %}

<figure><img src="https://3611830798-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F-MjbN1iGmN_HBnj_fyU9%2Fuploads%2FfJXhTboOC8hD8hoxHLtW%2F%E6%9C%AA%E6%A0%87%E9%A2%98-1.png?alt=media&#x26;token=a51f8f9c-aff5-4d84-b24a-45acfb6d193b" alt=""><figcaption><p>stripes of ligh &#x26; placing a plane outside the wall</p></figcaption></figure>

## 5. How do I achieve the effect of no precipitation but having standing water/snow?

1. <mark style="background-color:purple;">**Precipitation:**</mark> <mark style="background-color:purple;"></mark><mark style="background-color:purple;">Turn on precipitation in Environment - Weather, adjust the precipitation strength to 0, and then increase the puddle parameter appropriately.</mark>
2. **Decals:** The effect of water on the ground can also be achieved with a custom transparency map.

<div align="center"><figure><img src="https://3611830798-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F-MjbN1iGmN_HBnj_fyU9%2Fuploads%2FtfbSb9QzhWVsMg8JXXZZ%2Fimage.png?alt=media&#x26;token=565b7477-1fd8-41aa-933c-3f25d4f8590f" alt=""><figcaption><p>adjust the Precipitation strength to 0, and increase the Puddle</p></figcaption></figure></div>

## 6. Why is the custom HDRI/LUT file import not working?

<mark style="background-color:purple;">This will occur if the file path of the custom HDRI/LUT file contains special characters.</mark>&#x20;

It is recommended that the HDRI/LUT file be placed under an English path.

## 7. Why do scenes lose HDRI thumbnails?

There are two cases that can occur in the current version:

* Load an old archive and that archive uses the D5 inbuilt HDRI - Pure White;
* Download the HDRI from the D5 Assets Library - HDRI and import its local cache.

<div align="left"><figure><img src="https://3611830798-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F-MjbN1iGmN_HBnj_fyU9%2Fuploads%2Fg5GSdoOGVq50IAQCg6uH%2Fimage.png?alt=media&#x26;token=c847fa14-e638-4676-a857-34e957b6d479" alt="" width="334"><figcaption></figcaption></figure></div>

## 8. When keyframing the environment (Geo and Sky/HDRI), why does the scene flicker/have white spots?

<mark style="background-color:purple;">It's a current KNOWN ISSUE.</mark>

<mark style="background-color:purple;">It is relatively difficult to downsample in this case (when the scene environment changes), thus white spots/scene flickering may occur during preview or output.</mark>

Suggestion: When keyframing the environment in animations, if white spots/flickering occurs, it is recommended to output in two separate times and merge them in the post-production software.

<figure><img src="https://3611830798-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F-MjbN1iGmN_HBnj_fyU9%2Fuploads%2FN4LdRPxofJFvQFNXPBbz%2F0814%20(1).gif?alt=media&#x26;token=ed5c9a39-93c1-44dd-81dc-a5fd4760e3ef" alt=""><figcaption></figcaption></figure>

## 9. Why do scenes created in version 3.0 appear different when opened in previous versions?

When opening files saved in version 3.0 using previous D5 versions, **the manual exposure** and **fog effects** may alter, requiring manual adjustment of the parameters.